Power source load control

ABSTRACT

A method and apparatus for managing one or more grid supplied and separately metered power services, backup power sources, transfer switches and related powered loads using load monitoring and control which allow selectively connecting, disconnecting, limiting and controlling various loads which are powered thereby. The method and apparatus include operating with a system with a dual revenue meters providing grid power, a backup power source and a dual transfer switch wherein the power capabilities of each are economically sized while allowing reliability and convenience in selecting and powering loads. The connections to power sources and control of the loads powered thereby take into account various parameters including cost of power, load handling capability, type of load, load size, environmental factors, load usage during and subsequent to load connection, load priority and operator wishes.

This application is a continuation in part of, and incorporates hereinby reference in its entirety application Ser. No. 13/481,804 filed May26, 2012 titled Power Source Load Control which application in turnclaims benefit of, and incorporates by reference herein in theirentirety, provisional patent applications: Power Source Load Control,application No. 61/490,253 filed May 26, 2011; Power Source LoadControl, application No. 61/552,722 filed Oct. 28, 2011; Load Control,application No. 61/598,564 filed Feb. 14, 2012 and Genset OverloadControl, application No. 61/624,360 filed Apr. 15, 2012.

BACKGROUND OF THE INVENTION

The background of the invention, summary of the invention, briefdescription of the Figures, detailed description of the preferredembodiment, claims and abstract are presented and described herein to aperson having ordinary skill in the art to which the subject matterpertains, hereinafter sometimes referred to as person of ordinary skillor one of ordinary skill. Many people of ordinary or advanced skill inthe art commonly use words, for example such as generator and load, tohave language, location and context specific meaning. This usage workswell for providing understanding and clarity to a person of ordinaryskill, despite using words having several potential meanings. Forexample, valve is used in Europe in relation to vacuum tubes and inNorth America in relation to gaseous and fluid controls. Gas is used inthe U.S. to mean gasoline and the gaseous state of a substance. One ofordinary skill will know from the language, location and context usedwhich meaning of more than one possible meaning is intended.

As one example to demonstrate how the intended meaning is the knownmeaning to one of ordinary skill, consider a power generating devicewhich is often referred to simply as a generator by one of ordinaryskill, relying on the field of art and context of usage to supplyspecific meaning and limitations to the particular name generator. Aperson of ordinary skill writing a technical article about a backupgenerator used in the art of heating (or otherwise powering) a suburbanhome during loss of public utility power would know and intend generatorto mean an electrical generator. A person of ordinary skill writing atechnical article about a backup generator used in the art of heating abuilding in a large city during loss of public utility power would knowthat generator could be a steam generator. According to this example,depending on context, one of ordinary skill would know generator to meana steam generator or an electrical generator. As another example, in theelectrical power generating art generator is commonly meant to mean thegenerating device such as a motor or turbine and electrical alternatorcombination. As yet another example in the electrical art an electricalgenerator (often used in pre 1960's vehicles) outputs D.C. power and isdistinguished from an alternator (often used in post 1960's vehicles)which creates A.C. power which is internally rectified to provide theneeded D.C. power. Load may refer to the total load on a generator, oran individual load presented by a particular device, or may refer to thedevice itself which presents a load. The person of skill will recognizethe meaning of generator and load from the context in which it is used.

As set forth in more detail in MPEP 2111.01 (January 2018 [R-08.2017]revision is referred to herein), Applicant, as his own lexicographer,intends the words and phrases used in the specification and claims tohave their plain U.S. English meaning, that is, the ordinary andcustomary meaning given to the term by those of ordinary skill in theart, unless it is clear from the specification that they have been givena different (including narrower) meaning. When a word or phrase forexample such as a technical word or phrase has a meaning to one ofordinary skill from the location, context, usage, time frame and/or whatis well known in the art to differ from the plain U.S. English meaningas of the pertinent date, Applicant intends that meaning which is knownto one of ordinary skill to be used. As set out in MPEP 2182 a patentspecification need not teach, and preferably omits, what is well knownin the art. Thus, Applicant further notes that a meaning of a word orphrase which is well known in the art may not be specifically set forthin the instant specification other than by this note.

In a facility where a power source provides power to one or more deviceswhich each present a load or loads to the power source there is a needto determine and control which and how many loads are connected in orderthat the total of the loads does not create an overload. Overloads aregenerally undesirable in that they may cause deviation from power outputspecifications, loss of power, damage or combinations thereof. In theabove power source (generator) examples an overload could cause steam tonot be hot enough, or electric voltage to be too low or have the wrongfrequency. Additionally, management of the creation of power by thepower source, as well as the loads connected thereto is desirable forefficient operation.

A given power source has a maximum load handling capability dictated bythe power generation and delivery path (e.g. pressure, voltage, pipesize, wire size) or a maximum output (e.g. dictated by the design of thepower source and the system it is used in). For simplicity, devices thatmay be connected to the power source are often referred to in the artand herein as loads. For a given group of loads that are available forconnection, it may be desirable to inhibit a particular individual loadfrom being connected to the power source at a given time (e.g.preventing connection or disconnecting an already connected load) orduring a given time period or to restrict the power supplied to the load(e.g. by controlling coupling), or the power consumed by the load (e.g.by controlling the load). It may also be desirable to allow a given loadto be connected at a given time or during a given time period. Forexample, it may be desirable to inhibit the connection of a large loadduring times of high load demands, or to allow that load to be connectedand operated only during night hours when there is ample power availableand/or when fuel or energy rates are cheaper.

One of ordinary skill will recognize from the teachings herein that theinventive concepts given by way of example may be utilized for manytypes of power systems, including but not limited to hydraulic, fluid orgaseous heating, mechanical, thermal, solar, wind, liquid fuel, gasfuel, solid fuel and combinations thereof. The use of the invention withvarious types of systems will be known to the person of skill and inparticular by use of well known correlations between electrical, fluid,chemical and mechanical systems. For example, a voltage in an electricalsystem correlates to pressure in a fluid system, amperage to flow rate,wire size to pipe size, switch to valve, etc. While the presentinvention will be known from the teachings herein to have applicabilityto many forms of power sources and loads the background and teachingswill be given by way of example with respect to electrical generatorsand loads. The electrical generators used by example often include arotating power source and AC alternator combinations and are oftenreferred to in the art as generator sets, gensets or simply generatorsas well as by a host of other names which are frequently specific to theparticular type of energy source, power output and/or alternator used.

The connection and disconnection of power from the power source to theload is in general controlled by one or more switch and it will beunderstood that there are many types of switching mechanisms that mayperform such connection and disconnection. When speaking of switch,switching, connection or disconnection it will be understood that suchaction is not meant to be restricted to a particular type of switch orconnection unless the type is specifically enumerated or is apparentfrom the context. For example, when teaching connecting, coupling orswitching power from an electrical generator to an electrical load itwill be understood that the action is performed by an electricalcircuit, for example a switch but the teaching is not otherwise limitedto a particular type of electrical switch unless specificallyenumerated. If the teaching is with respect to controlling the amount ofcurrent or load (as compared to simply switching the current or load onor off) it will be known that a simple on/off type of switch is notmeant and the switch must be some sort which can control the amount ofcurrent.

Often there are multiple types of electrical devices available to beconnected to and powered by the power source. Some devices may simply beturned on and off and some devices have loads which will vary with timeor environment. A maximum load can occur when all devices are powered atthe same time and each device presents its individual maximum load tothe power source. As a simple example, it is possible to turn on all ofthe lights and appliances in a house, but that rarely happens. In manysystems maximum loads are rarely presented to the power source and thetypical load is frequently much less than the maximum load. That causesa system design problem because it is necessary for the power source, inthe present example an electric generator, to provide power to themaximum load to prevent overload but that capability generally makespowering the typical load inefficient.

By way of background one of ordinary skill will recognize that severalfactors are involved in both the amount of power that can be supplied bya power generator and the amount of power consumed by a particulardevice which is being powered. The output of a wind turbine is dependenton the amount of wind and the design of the turbine. A solar cell arrayis dependent on the amount of sunlight and the design of the array. Anelectrical generator is dependent on the mechanical power available toturn the alternator. For a typical liquid or gaseous fuel powered backupgenerator, the maximum output is dependent on the size of the internalcombustion engine, the alternator and its operating conditions.

With respect to internal combustion engine powered electrical generatorsthe maximum power available and transferred to a load for a given sizegenerator is generally dependent on many factors such as the generator'sinternal temperature, ambient temperature, humidity, altitude andbarometric pressure, type of electrical connection (e.g. voltage andsingle or multiple phase), power factor of the load, fuel quality, fueldelivery rate and duration of the load. Generally, the internaltemperature of the engine is a factor in determining the safe maximumoutput of the engine and the internal temperature of the alternator is afactor in determining the safe maximum current output from thealternator. Internal temperatures of the engine and alternator aredependent on load, ambient temperature, altitude, barometric pressureand humidity, among other factors. Engine efficiency is also dependenton various fuel and air quality factors. A generator can usuallywithstand higher currents when it is cool but those currents will soon(often in the matter of a few minutes) cause additional internal heatingwhich in turn limits the maximum output current. Electrical generatorsoften have two maximum power ratings, one for generator use as a backuppower source and one for use as a prime power source. The prime powermaximum is usually lower in part due to the continuous operation.

Efficient operation of such generators is usually a consideration in theselection of the generator which in turn leads to a need for the presentinvention to manage the load presented to the generator. As an example,consider the specifications of a Cummins model GGHE 60 kW electric powergenerator which includes an AC alternator which is driven by a 6.8 literV10 internal combustion engine using natural gas as fuel. Electric powergenerators of this type are commonly used for backup power in largehomes and small businesses to provide power in the event utility companypower fails. Assume for this example that this generator is chosen topower a home which can present a maximum load of 60 kW to the generator,but a typical load is only 15 kW.

At the full load output of 60 kW the natural gas fuel consumption forthis generator is 24.4 cubic meters per hour (m³/hour). One might thinkthat at ¼ load this generator would burn fuel at approximately ¼ of thefull load rate or 6.1 m³/hour. That assumption is incorrect howeverbecause the generator is much less efficient at ¼ load. The fuel burnrate for a 15 kW load is actually 10.6 m³/hour or about 43% of the fullload rate. Among the several reasons for the inefficiency at lower loadsis that the alternator and the big V10 engine's entire cooling systemmust be sized to handle heat output at full load. The coolant pump ispumping coolant through the engine and radiator, the fans are pullingcooling air through the alternator, across the engine and blowing airthrough the radiator thus performing maximum alternator and enginecooling whenever the engine is running. This cooling causes aconsiderable drain of engine power, even though all of that cooling isnot needed for the 15 kW load. Other efficiency robbing factors such asengine friction and alternator windage are higher than needed for thetypical load because of the design to handle maximum load.

If instead a less expensive Cummins model GGMA four cylinder generatorrated at 20 kW were used as the power source, the natural gas burn ratewhen powering the typical 15 kW load is only 7.6 m³/hour. Using thesmaller 20 kW generator is less expensive to purchase and operate andthus more efficient for the typical load. Unfortunately, the 20 kWgenerator is unable to handle the 60 kW maximum load, which if connectedto the generator would cause the generator circuit breaker to trip andall power to the load would be lost. As will be described herein thepresent invention will find use in such applications where a generatoris unable to power the maximum load which can otherwise be presented toit.

With respect to the power required by a particular load several factorsmay be involved depending on the load type. Several examples of varyingload will be briefly described to aid in understanding the invention. Itwill be understood that for most devices the voltage applied from thegenerator is substantially constant and consequently the current drawnby the device is proportional to the load on the generator. When thevoltage from the generator is substantially constant the currentsupplied directly corresponds to the power supplied and vice versa andeither may be measured to obtain the other as is well known to one ofordinary skill. Many electric motors have a large starting current for afew seconds followed by a running current which depends on themechanical work the motor is doing. For a motor such as one powering avacuum cleaner that work depends on the amount of suction being createdat any particular time which in turn depends on the technique of theperson operating the vacuum. Heating appliances such as ovens oftenrequire more current to initially heat up than to maintain temperatureonce it is heated. This change is due in part to temperature dependentresistance changes of the heating elements.

An air conditioner will require a large starting current for a few ormany seconds depending on the head pressure of the compressor pump andmass of the armature of the compressor motor and the moving componentsof the compressor pump. Once the compressor is up to operating speed theamount of current necessary to maintain that speed depends on the headpressure which in turn is partially dependent on the temperature of thecondenser coil which in turn is dependent on ambient temperature and airdensity. If a compressor loses power the built up head pressure willtake several dozen seconds or even minutes to bleed off through thecapillary tube or expansion valve in the evaporator and if an attempt ismade to restart the compressor before that head pressure has dissipatedthe starting current will be very large. If the head pressure is toohigh it can cause the compressor motor to stall which in turn will causeone or more circuit breakers to trip and remove the voltage supply fromthe compressor, thus care must be taken to not start the compressor tooquickly after it has stopped. This can be an issue when utility power islost and a backup generator is started to replace that lost power.

A battery charger used for example to charge the batteries in anelectric or hybrid vehicle or the like, can change its load to the powersource based on a variety of factors including the internal temperatureof the batteries and their amount of charge. Generally, the chargingcurrent is decreased with increased temperature and as the batteriesapproach full charge. The control of battery charging current,especially in large battery arrays used with electric and hybridvehicles and the like is well known in the art. For example, U.S. PatentApplication Publication 2010/0134073 assigned to Tesla Motors, Inc.describes an elaborate manner in which battery charging current,temperature and various other factors are controlled, which Publicationis incorporated herein by reference in respect to its prior artteachings. It may be noted that by controlling charging current, themaximum load drawn from the power grid or generator can be controlled.

Tesla Motors, Inc. offers a high power connector which allows itsvehicle to be connected to common 240 volt AC power circuits to chargethe batteries. The Tesla Motors High Power Connector, or HPC includes amaximum current selector switch that is manually set at the time ofinstallation such that the maximum amount of current which the chargeris allowed to draw from the 240 volt circuit is limited according to thecapability of the circuit connection to the supply. For example, if a 40amp circuit is used, the switch on the HPC is set to limit the HPCcurrent draw to 32 amps. This is an important feature of the HPC becauseeven though the charger is capable of operating with a 240 volt, 90 ampcircuit for fast battery charging, many homes only have a 100 ampservice connection and thus are incapable of providing current to theHPC via a 90 amp circuit without risk of overloading the service andtripping the main circuit breaker.

Returning now to the operation of a system having a variety of loads, inorder to prevent sustained overloads and decrease the possibility of acircuit breaker trip or damage to a generator, especially those used forbackup power, there are prior art systems which detect when a generatoris in an overload condition and switch off loads. This operation isknown as load shedding. Load shedding is well known in the prior art,for example a system is described in the Rodgers et al. U.S. PatentApplication Publication 2005/0116814 which Publication is incorporatedherein by reference in respect to its prior art teachings. Paragraphs70-115 are particularly pertinent. Importantly load shedding takes placewhen the load is connected and overload detected as described in moredetail in this Publication.

Load managers for load shedding are commercially available, for examplethe Generac Nexus automatic transfer switch used in conjunction withbackup power generators has a load manager option. These devices, whichwill be explained further below in respect to FIGS. 1-3, operate tostart a gaseous or liquid fueled backup generator to power homes andbusinesses whenever power from the local power company fails andtransfer the load from the local power company to the generator. ThisGenerac transfer switch contains multiple switches, a main high currentswitch (e.g. 400 amps) for switching between the power grid andgenerator as the source of power for the home or business. It includesadditional low current secondary switches to provide control voltageswhich are used to disconnect low priority loads via load managers suchas the Generac DLC load control Module (contactors) when the generatoris overloaded.

Most generator engines utilized for North American home backup systemsrotate at 1800 or 3600 RPM, that rotation being coupled to an alternatorthat provides AC power at a standard 60 Hz frequency. When overloadedthe rotation of the engine slows because the engine can not produceenough torque to keep the alternator rotating at the correct speed. Theslow engine in turn causes the frequency of the AC power to decrease.The rotation and corresponding AC power frequency may drop substantiallyin the presence of a large overload and the engine and alternator caneven attempt to rotate against their mounts, much like an automobileengine attempts to rotate against its motor mounts during heavyacceleration. The Nexus transfer switch includes technology whichmonitors the frequency of the AC power from the generator and sheds allof the low priority loads after the generator has been overloaded.Nonessential circuits (low priority loads) are shed by opening thesecondary switches when the frequency of the AC power provided by thegenerator drops below 58 Hz (for 60 Hz systems). The secondary switch isused to control a circuit to apply or remove voltage to a contactor tocontrol applying and removing a corresponding load on the generatorthereby removing the overload when the contactor is opened. Importantlythis load shedding takes place after the overload happens.

Frequency detectors have tolerances which must be accounted for to avoidfalse tripping so there is a tradeoff in the speed of detection of offfrequency condition vs. false detection due to frequency detector erroror allowable momentary frequency deviation. For example, if thefrequency threshold for disconnecting the load is set at 58 Hz,inaccuracies in frequency detection may cause an overload to be falselydetected and a load disconnected when no overload exists. It is possiblethat a combination of overload, say one which slows the frequency to 58Hz and inaccurate frequency detection, can cause an actual overload togo undetected. Unfortunately, the overload, and possibly damage to thegenerator or its load, may have already happened by the time theoverload is detected. Despite the various shortcomings in using powerfrequency as an indicator of generator overload, it will be understoodfrom the present teachings that this is nevertheless an inexpensivemanner of detecting and removing overloads, as will be taught further inconnection with load limit and load switch operations.

As another example if an oven is turned on at the same time a stormdrain pump automatically starts, it is still possible that the generatorcircuit breaker will trip before the overload can be detected and theexcess load removed, thus all power will still be lost. Turning on anoven at night during a storm and having all power go off because thegenerator circuit breaker improperly tripped can be extremelytroublesome, not to mention the inconvenience of having to find andreset that circuit breaker. At the least, it is inconvenient for someonein the home to turn on a device, only to have it or some other device(s)automatically disconnected from power shortly thereafter. In a homebackup system that device causing the overload might be something thatis needed in a timely fashion such as a medical device, lighting, acooking appliance, a television, garage door opener or other importantdevice. In most situations it would be better to have a nonessentialload such as a vehicle battery charger turned off or limited to preventany overload.

SUMMARY OF THE INVENTION

It will be understood from the present teachings that it is desirable tocontrol the total load presented to a particular power source to keepthat load at or somewhat below the maximum capability of the powersource. Alternatively, it may be desirable to control the total load tokeep the power source at or near its optimum power output to achievehigh or maximum efficiency. As part of controlling the load to the powersource it is desirable to connect some or all loads according to apriority. It is also preferred to alert the user that power is notavailable to power a particular device and allow the user to decide whatto turn off or leave off than to have the device (and possibly severalothers) turned off shortly after it is turned on due to actual orpotential overload. If loads are available that may but do not need tobe connected and operated, it may be desirable to wait and operate themwhen the power source is operating well below its optimum efficiency. Bywaiting an increase in the efficiency of the operation is achieved withthe added benefit of avoiding having to disconnect loads when the powersource is operating at or somewhat below its maximum capability and anunexpected additional load is applied. Thus at least these two modes ofoperation are desired to be provided to facilitate reliability andefficiency, operation at or somewhat below maximum output capability andoperation at, near or closer to optimum power source output.

It will be understood by one of ordinary skill that short term largeloads may be allowed in that many engine driven alternator systems aredesigned to permit short term increases in power output above themaximum power that can be continuously delivered. As used herein and inthe claims, overload means a load that if not disconnected or otherwiseprevented will either cause a departure from specifications for thepower output from the power source, for example such as a deviation ofAC power voltage or frequency for longer than a specified time period, aloss of power such as from a tripped circuit breaker, or damage such asoverheating or exceeding mechanical stress limits.

When making decisions which are aimed at efficiency, one substantialconsideration is the cost of providing power. If power can be obtainedfrom the electric utility or elsewhere at lower cost during certaintimes, for example during the night, the invention can be utilized tocontrol loads in a manner to best take advantage of the lower costpower. This can be done while still ensuring that the devices presentingthe loads are available for use at other times if needed. Such use caninclude the device's intended function or use by a user, or as a load toimprove power source efficiency. For example, a battery charger forcharging an electric or hybrid vehicle or the like can charge thebattery to a given level such as half full, immediately upon beingconnected. This will ensure the vehicle is quickly available for use.The remainder of the charging from half to full charge can be delayeduntil lower price electricity is available. The delay of the remainingcharge can also be used to boost an under utilized power source such asa backup generator closer to its optimum output for improved efficiency.Thus, it is desired to control a charger to charge at a given rate assoon as connected until a first level of charge is reached and thencharge at the same or another rate starting at a later time andcontinuing until a second level of charge is reached.

The delay of operating a load can be coordinated with maintenance of thepower source to provide a load for the maintenance without wastingpower. Most backup generators are controlled in order that they areoperated periodically, with or without a load, for example 30 minutesevery week. This is known as exercising and it helps to keep fluidscirculating, bearings oiled, moisture dried, etc. to improvereliability. A load such as a battery charger can be delayed until anupcoming scheduled exercising when the battery is charged.Alternatively, the battery can be charged at a convenient time byrescheduling the exercising. More generally loads may be supplied withcurrent at a first known amount (which may be an amount to achieve aparticular effect such as charge rate) starting at a known time (whichmay be upon connection or a clock time) for a known period of time(which may be the time to achieve a particular event or a particularclock duration) followed by one or more known combinations of the aboveknown amount, known time and known period. As one example, charging abattery at full rate until half full upon connection upon return to homein the evening then charging at the maximum available current during thetime period of generator exercise followed by charging at a mostefficient charging rate during off peak hours when grid power is cheapwith each of the times being terminated early if the battery reachesfull or some other desired charge level.

The invention can also be configured to allow selection of the powersource to power one or more loads from among a plurality of powersources, for example a load can be powered from a low cost source suchas photovoltaic solar cell panels, a wind turbine, fuel cell, flywheelor powered from the utility company power if there is insufficient sunand wind or if more power is needed than the solar panel, wind turbineand/or fuel cell can provide. This operation may be coupled withefficient utilization of sources such as to charge a vehicle battery asdescribed above. Changing to other power sources can be accomplished byany means or method known to the person of ordinary skill, e.g. viatransfer switch, parallel input connections to the load, parallel powersources.

The invention described herein allows efficient matching of a total loadmade up of individual loads to one or more power sources withoutoverloading the power sources. The present invention will allow sizingof power sources to accommodate less than the maximum possible load andcan prevent overloading of the power source by preventing a load whichwould otherwise immediately cause or which could lead to a futureoverload from being connected or alternatively by restricting the powersupplied to that load and/or others. This operation is achieved by theintelligent connection and disconnection of individual loads as well asthe control of the power drawn from power sources by connectedindividual loads and/or control of power supplied to connectedindividual loads as will be described in more detail below.

Most commercial generators are well characterized for operations undervarious conditions, including but not limited to loading andenvironmental conditions, and the maximum available output power isknown for any particular set of such conditions. The present inventionis preferred to sense one or more of the various conditions which affectthat maximum available output power and use those conditions along withthe characterization of the generator to determine precisely what thatmaximum available output power is at a given time, what the expectedavailable power will be at one or more times in the future as well asthe present and future effect the connection of a particular load mayhave on available power. In that fashion the present invention canselect loads to be connected to the generator or other power source topower the maximum number of loads and/or to operate nearer to or achieveoptimum efficiency while at the same time monitoring the present andexpected future load thus ensuring that the generator will not beoverloaded instantly or during the duration of any particularconnection.

The description of the preferred embodiment of the invention herein ismade by way of example as an improvement to an electrical backupgenerator system to provide power to a typical home or small business inthe event power from the power grid (i.e. the municipal utility power orstreet power) is lost. The preferred embodiment may also be utilizedwith more than these two (grid and backup generator) power sources, forexample wind and solar power sources may be incorporated with grid andengine driven power sources. It will be understood to one of ordinaryskill from the teachings of the preferred embodiment that the inventionas herein described is not limited to the particular embodiment and theinvention may be practiced in a manner to be utilized with other typesand combinations of power sources and loads to achieve a desired levelof performance for a particular system.

The elements and steps of the preferred embodiment are preferred to beimplemented with electronic circuitry as will be well known to one ofordinary skill from the present teachings. As used in the description ofthe preferred embodiment, circuit is meant to be an electric orelectronic circuit unless it is clear from the context that it isanother type of circuit. Descriptions of, and nomenclature pertainingto, elements of the invention are given in respect to names ofelectrical and electronic devices or operations (e.g. switch, generator,processor or processor circuit, power grid, solar panel, wind turbine,fuel cell, communications, communications channel, interface orinterface circuit) or a descriptive name of a function performed withrespect to some device or condition (e.g. load monitor, generatormonitor, load control, load switch, communications link) all as are wellknown to one of ordinary skill from the teachings of the preferredembodiment of the invention and context of usage. In some instances, thename of the device is also descriptive as will be well known to one ofordinary skill.

The invention described herein is preferred to utilize intelligenttiming for connecting and disconnecting of loads to one or more powersources including control of power supplied to or demanded by the loadsin order that the total load on any one power source is kept at or belowthe maximum output capability of that power source, or alternatively ator near an optimum efficiency level, which may be at or below themaximum capability. The decision making used by the preferred embodimentof the invention for connecting, supplying and/or controlling aparticular load to the power source is preferred to be responsive to thecapabilities of the power source and the type of load to be connected(including one or more parameter of each), the priority or importance ofthe load to be connected, the timeliness of the load connection,environmental parameters which affect the power source and loads and theinput of one or more persons desiring to use a device presenting aparticular load. As used herein and in the claims, parameter means aquantity of one or more property or attribute (e.g. of a device,physical property, substance or environment) which is treated as aconstant. A parameter may at times change or be adjusted. Examples ofparameters of interest herein include various horsepower, mechanicalload, temperature, pressure (including altitude), humidity, power,wattage, voltage, current, including maximums, minimums, safe, starting,limited, instant, real time, near real time and timely. Quantitiespertaining to parameters may be in analog or digital form and expressedas numbers which are suitable for use by the device(s) using orresponsive to such parameters.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a simplified flow chart of a prior art transfer switch andgenerator controller having elements 1-11.

FIG. 2 shows a simplified circuit diagram of a prior art power backupsystem having power grid 12, generator 13, generator and transfer switchcontroller 14, transfer switch 15 a, load main panel 15 b, load subpanel 15 c and loads 16-20.

FIG. 3 shows a simplified circuit diagram of a prior art power backupsystem having power grid 12, generator 13, generator and transfer switchcontroller 14, transfer switch 15, loads 16-20 and load manager elements14 a.

FIG. 4 shows a simplified circuit diagram of a power backup system whichincorporates a first embodiment of the present invention, the systemhaving power grid 12, generator 13, transfer switch 15, loads 16-20,optional environmental, user & misc. sensors 21, load switches 22 a-22c, load monitor 23 a, generator monitor 24, load control 25 a andcommunications links 26 a-26 c, 27 b and 28 a and optionalcommunications links 27 a, 28 b and 28 c.

FIG. 5 shows a circuit diagram of load control 25 a with communicationslinks 26 a-26N, 28 a, 30, 31, 32, optional communications link 28 b,interfaces 29 a, 29 c-29 h, optional interface 29 b and processorcircuit 33 a.

FIG. 6 shows loads 16-18, load switches 22 b & 22 c, load monitor 23 b,communications links 26 a-26 c, 36, 40 a, optional communications link38, 40 b, interfaces 29 i-29 k, 35, switches 34, and user input and userfeedback module 39. FIG. 6 also includes Load Limit 43 having currentcontrol circuit 44.

FIG. 7 shows user input and user feedback module 39, display 41 and userinput keys 42 a-42 c.

FIG. 8 shows a simplified circuit diagram of a power backup systemsimilar to FIG. 4 which is a more elaborate embodiment of the presentinvention, the system having power grid 12, generator 13, transferswitch 47, loads 16-19 and 48, environmental, user & misc sensors 21,load switches 22 b and 22 c, load monitors 23 a and 23 c, power sourcemonitor 49, load control 25 b, communications links 26 a-26 c, 27 a, 27b, 27 d, 28 a, 28 c, 45, 46, optional communications links 27 c, 28 b,load limit 43 and third power source 50 having power output via 51.

FIG. 9 shows a more detailed circuit diagram of load control 25 b withcommunications links 26 a-26N, 28 a, 30, 31, 32, 45, 46, optionalcommunications link 28 b, interfaces 29 a, 29 c-29 j, optional interface29 b and processor circuit 33 b.

FIG. 10 shows a simplified diagram of the embodiment of FIG. 8 whichincludes elements 12, 13, 16, 17, 18, 19, 22 b, 22 c, 25 b, 26 a, 26 b,26 c, 27 a, 43, 45 and 47 as in FIG. 8. FIG. 10 also includes elementsfor recovering heat from generator 13 including heat exchangers 52 and53, electrically controlled valves 54 and 55, valve control circuits 56and 57, generator heat supply 58, generator heat return 59, domestic hotwater supply 60, cold water supply 61, radiant heat supply 62, radiantheat return 63, domestic heat temperature sense link 64 and radiant heattemperature sense link 65.

FIG. 11 shows a simplified diagram of a combination load and powersource which the invention may be utilized with including battery 68,battery charger 66, DC to AC inverter 67, connection to transfer switchoutput 71 a, communications connections to load control 69 and 70.

FIG. 12 shows a simplified diagram of an embodiment of the inventionwhich is used with an energy storage battery 68 and optional generator72 communicating with load control 25 b via optional communications link73 with battery 68 usable as a backup power supply in the event of apower grid failure. FIG. 12 includes power grid 12, loads 16-19 and 48,load control 25 b, load switches 22 b and 22 c, load limit 43,communications links 26 a-26 c, 45 and 46 and transfer switch 47, as inFIG. 8 and including battery 68, communications links 69, 70 as in FIG.11. Battery charger 66 the same as in FIG. 11 is connected to the outputof the transfer switch 47 via 71 c, and DC-AC inverter 67 the same as inFIG. 11 is connected to an input of transfer switch 47 via 71 b.

FIG. 13 shows a simplified diagram of a combination of load coupler 80shown by example configured with typical air conditioner load 18 forcoupling the load to the power source, in this example power from thetransfer switch. Load coupler 80, described further with respect toFIGS. 14 and 15, may be utilized for an implementation of any of theload switches 22 if desired and communicating with load control via link26 c. Load coupler 80 may also be configured with a current controlcircuit 44 (not shown), with or without a relay, to be utilized as aload limit 43 for those types of loads which may utilize controlledcurrent, as described herein.

FIG. 14 shows a detailed diagram of the preferred embodiment of loadcoupler 80 of FIG. 13 having current sense 23 d, relay 34 which may belatching or simple type, optional current control 44, relay positioncircuit 79, battery & charger 74 responsive to power from the transferswitch to provide backup power 75, wireless communications link circuit29 k receiving backup power and coupled to antenna 76 (which may beinternal or external to 80) to communicate wirelessly with load controlvia channel 26 c. Also shown is microprocessor circuit 37 powered bybackup power 75 and responsive to current monitor shown as sense 23 d,transfer switch power voltage monitor 78, and relay position circuit 79,with 37 controlling relay 34 and interfacing with wirelesscommunications link 29 k and user interface 77 which may also receivebackup power 75 if desired.

FIG. 15 shows a commercially valuable embodiment of load coupler 80which is physically separated into two sections, a high voltage section80H and a low voltage section 80L having multiple and various circuitconnections 82 for connecting internal circuits of each section to theother and/or external devices. High voltage section 80H is configured tocontrollably couple power from the transfer switch to a load 18 shown byexample as via an externally controllable latching or simple relay 34having relay position circuit 79, section 80H further including currentmonitoring shown as sense 23 d. FIG. 15 also shows a power supply 81coupled to the power from the transfer switch, the power supplyproviding power, which is preferred to be a lower voltage safe for humancontact, in response thereto.

FIG. 15 section 80L includes a battery and charger circuit 74 to receiveAC (or DC) voltage from an external source 81 to provide regular andbackup power 84 preferably made available to external devices via one ormore connection 82, the battery and charger circuit 74 also providingregular and backup (DC or AC) power 75 (hereafter referred to as backuppower) for internal use in 80L, a microprocessor circuit 37 is poweredby backup power 75 and responsive to current sense 23 d (located in80H), voltage monitor 78 (from transfer switch power via supply 81) andrelay position circuit 79 with microprocessor circuit 37 operative toprovide control signals 85 via external connections 82 and withmicroprocessor circuit 37 also operating to control relay 83 which relayhas connections 82 for external circuits. Connections to some externalcircuits are preferred to be protected via protection devices (circuits)86. Microprocessor circuit 37 further interfaces with wirelesscommunications link 29 k (which is powered by backup power 75) havingantenna 76 and operating to communicate with load control(s) viawireless communications channel(s) 26 c. Microprocessor circuit 37 isalso coupled to user interface 77 (which may receive backup power 75 ifdesired) and to connections 82 via protection device 86

FIG. 16 shows a further embodiment of a load limit 88 controlling anoven 16 wherein a load control 25 c responsive to the input power via 87is incorporated with 88 along with a current control circuit 44 andcurrent sense 23 d.

FIG. 17 shows a further embodiment of a load switch 89 controlling aclothes dryer 17 wherein a load control 25 d responsive to the inputpower via 87 is incorporated with 89 along with contactor 34.

FIG. 18 shows the further embodiment of load control 25 c including atransformer 81 responsive to the input power via 87, a power supply 74,frequency measurement circuit 90 responsive to the frequency of theincoming power, user display 90 for displaying messages to a user, userinput 92 by which a user inputs information and/or commands, timebase 93facilitating timing measurements, current measurement circuit 95responsive to 23 d, switch/limit driver 94 coupled to current control 44(or alternatively 34).

FIG. 19 shows a still further embodiment of a load control processor 99and dual transfer switch 100 which is preferred to be utilized insystems which have regular or normal utility company metering as well astime of service (TOS) metering for example when a utility companycustomer can purchase electricity at preferred rates. The embodimentshown includes a normal billing power input 104 to the transfer switchfrom a first meter 96, a TOS power input 106 to the transfer switch froma second meter 98, a single backup power source input 105 to thetransfer switch from a backup power source 97, a transfer switch 100including load monitor 23 e, contactors 111 receiving power via 104 and112 receiving power via 106 and having on-off-on throws. Both 111 and112 have backup power contacts which are electrically paralleled in 100to receive backup power from 97 via a single input 105. FIG. 19 furthershowing alternate and optional load monitor locations 23 f-i, a normalbilling output 101, a TOS billing output 102, a load control processorcircuit 99 receiving input from and optional output to EnvironmentalUser & Misc. Devices 21 via 28 c, receiving from and optionallyoutputting to Backup Power 97 via 107, receiving input 108 from loadmonitor 23 e, receiving input 109 from 96 via 104, and input 125 from 98via 106, providing output 110 to the contactors 111 and 112. The loadcontrol processor circuit 99 also has N output(s) 103 to N controlledloads.

FIG. 20 shows an embodiment of the transfer switch 100 as used with apower grid 12 and including a novel dual meter 113 having a singularmeter socket 113 a the dual meter operating to receive power from thegrid via a single input from the meter and provide two outputs 104 and106 via the meter socket which outputs are metered respectively bywatthour meters 96 a and 98 a. The two power outputs are coupled via aservice disconnect 123 having service disconnect sections 123 a and 123b with a common trip 123 c, the novel transfer switch 100 having aninput for receiving grid power from 104 via 123 a and input forreceiving grid power from 106 via 123 b the transfer switch 100 having asingle input for receiving power via 105 from a backup power source 97,which may be controlled via 107, and outputting power via 101 and 102which are monitored by 23 h and 23 i respectively. The load controlprocessor 99 is responsive to power from 97 via 105 in order to switchthe transfer switch contactors as well as well as 23 h and 23 i tocontrol controlled loads via 103.

FIG. 21 shows an embodiment of the transfer switch 100 a similar to 100,but without the center off positions, and including the grid power inputcircuit to the dual meter 129. As with FIG. 20, power flows from thepower grid, through one of the dual meters, through the dual transferswitch 100 a contacts of the contactors and flows out from therespective normal billing and time of service billing outputs to thenormal and time of service loads. When grid power fails the load controlprocessor switches the contactors to enable power to flow from thebackup power source 97 through the respective contactors to the loads.

FIG. 22 shows front (or face), right side and back side (or base) viewsof the dual meter 113 including TOS and normal wattmeter readouts 96 band 98 b, meter cover 127, baseplate 128, mounting ring 128 a, inputblades 129 a, normal output blades 104 a, TOS output blades 106 a andcommon blade 130. FIG. 22 includes alternate back side view of 113showing baseplate 128 with alternate input blade arrangement 129 b and129 c.

FIGS. 23A-23E show a simplified mechanical drawing demonstrating a noveltransfer switch contactor section which may be utilized as a doublethrow or double throw with center off contactor 114. The switch may beutilized sections with each section switching a circuit of single ormultiple phase power connection as in 100 or 100 a. The swingermechanism of Contactor 114 is shown in FIG. 23A including a conductingmetallic swinger 115, the swinger having a pivot point about which theswitch in the Figure rotates causing the contacts to rotate up and downand the spring loaded shaft 118 to rotate up and down in the oppositedirection. The swinger 115 is operated by an insulated cam 116 securedto a shaft 117. The swinger further includes a telescoping, springloaded shaft 118 which presses against an insulated detent plate 119 tohold the contacts in an upper, center or downward position. The swingercontacts are electrically connected via the metallic structure of theswinger to an electrical conductor C.

FIG. 23B shows a contactor 114 in the center off position, along withthe mating upper and lower contacts which are connected to terminals A1and B1 respectively and the swinger further connected to terminal C1. InFIG. 23C, the A-C contact position is shown and in FIG. 23D the B-Ccontact position is shown. The swinger may be rotated by the insulatedcam 116 enabling the swinger to connect C to either the terminal A viathe A-C contacts or the terminal B Via the B-C contacts or neitherdepending on the position of the cam.

FIG. 23E shows a front (terminal end) view of a bank of four contactorsections 114 as may be used in a single phase transfer switch 100 ofFIG. 19 and having cams 116, shaft 117, solenoids 120, 121 and 122operating to rotate shaft 117. Contacts with suffixes 1 and 2 correspondto the single line circuit e.g. contactor 111 of FIG. 19 and contactswith suffixes 3 and 4 correspond to the single line circuit e.g.contactor 112 of FIG. 19. The A3 and A4 terminals are replaced with bussbars 124 and 126 connecting to A1 and A2 respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1-3 provide background for understanding of prior art electricalpower backup power systems as they pertain to the present invention. Oneof ordinary skill will already know these systems and the FIGS. 1-3 aresimplified to aid in understanding some of the shortcomings of the priorart which are overcome by the present invention. As just one example, itwill be known that the connections shown in the various FIGS. 1-3 (and4-21D) often represent a plurality of actual circuits, such as theconnection from the utility power grid 12 which may entail severalconductors ranging from three for a single phase system to six or evenmore for multiple phase systems.

FIG. 2 shows a prior art power backup system to power some of the loads16-20 utilizing a service connection to a power grid 12 as the primarypower source and a generator 13 as the backup power source. As is wellknown in the art, the figures herein, including FIG. 2, are drawn insingle line form, that is, a single line represents the multipleconductors of the flowing single or multiple phase power. For theexamples herein, the power grid is subject to loss of power or powerfluctuations (e.g. brownouts) and supplies power where the cost of thepower varies from time to time. Generator 13 is used in the prior artand preferred embodiment examples with respect to an electric powergenerator having an internal combustion engine powering an alternator.It will be understood that power sources, loads and other elements ofthe described systems of the present disclosure have various parametersassociated with them. Some parameters for example are the maximum outputpower of a source, which maximum output may change from time to time,the power output (e.g. timely, current or at the present time poweroutput) of a source, the maximum power consumption of a load whichmaximum consumption may change from time to time, and the powerconsumption (e.g. timely, current or at the present time consumption) ofa load. Such parameters may be a singular parameter for example such asa maximum voltage, wattage or current, or a plurality for example suchas voltage and power, may include other factors such as a time orenvironment related factor, such as a maximum current at a giventemperature or for a limited time. Load parameters, e.g. expected ormaximum watts or current consumed by a load, and maximum output powerparameters, e.g. maximum watts or current that can be provided by apower source, are of particular importance herein.

In typical installations the power grid 12 is connected via a serviceconnection to the transfer switch 15 a and distribution panels 15 b and15 c all of which have a maximum rating. The service connection has acircuit breaker to prevent the total of the loads being powered (i.e.the total load) from exceeding that maximum rating of the serviceconnection. In particular there is a circuit breaker (known as the mainbreaker) located on the power grid service, usually at the power meter,which will be known to disconnect all power to the transfer switch 15and main panel 15 b if it trips. There will also be a circuit breakerlocated in the generator 13 to disconnect all power from the generatorwhen it trips. Obviously, having either of these circuit breakers tripis a serious inconvenience, especially if it happens when there isnobody available to reset the breaker, or during a storm, at night orother inconvenient time. Additionally, each panel has circuit breakerswhich will trip and protect individual loads if too much current isconsumed.

It will be understood that generator 13 is intended to also representother power source devices to provide power in a desired form from powerin another form or from stored energy. Generator 13 may for example be awind turbine, solar panel, fuel cell, flywheel, battery, water, wind orsteam turbine and may incorporate a DC to AC inverter circuit, generatoror alternator to provide electricity if that is the desired output.Stored or collected power may come from gaseous, liquid and solidsources (e.g. fuels) such as hydrocarbons like natural gas, gasoline andother petroleum or solid hydrocarbons like coal, biomass sources, waterpower such as tides, waves and reservoirs, wind, sunlight, chemical andnuclear energy such as batteries, fuel cells, reactors, mechanicallystored energy such as stored heat, flywheels, weights and compressedgas, and other forms as will be known to one of ordinary skill. Somedevices may be both power sources and power loads, and store energywhich may be converted back to AC (or DC) power to provide backup power,heating, to store in another form or to sell back to the electricutility. For example, in respect to battery storage of energy, it isnoted that the batteries in an electric or hybrid vehicle or the likemay be used as both loads and power sources.

When used with a primarily electrical circuit, generator will mean anelectric generator which is compatible with that type of electricalcircuit. Names such as electric generator (which primarily outputs atleast electric power), AC generator which primarily outputs at least ACelectric power), steam generator (which primarily outputs steam power),solar panel (which uses solar energy as the source of output power),fuel cell (which uses liquid or gaseous fuel and a chemical reaction ina cell to output power), electric solar panel or electric fuel cell(which additionally mean to output electricity). As an example of thetype of generator being known from context, a generator which providespower to a transfer switch and thereby provides backup power in place ofan electric power grid which has failed, will be understood from thecontext (i.e. to replace electric power) to be an electric powergenerator. Generally, the type of device being referred to in thespecification and claims will sometimes be specifically named, but whennot specifically named will be generically named (e.g. generator) and ifintended to refer to a specific device that device will be apparent fromthe context. As just one example, transfer switch may be any type ofswitch, e.g. electrical, gaseous (e.g. steam) or hydraulic but if usedin an electrical system to transfer electric power will be known to bean electrical type of switch and if used with a steam system to transfersteam power will be known to be a gaseous type of switch, e.g. valve.The teachings herein with respect to the preferred embodiment ofelectrical systems will nevertheless be understood to be applicable toother types of power systems.

FIG. 2 shows a simplified diagram of a prior art backup generator systemof the type the preferred embodiment of the invention may be used with.Electrical power from power grid 12 is normally supplied via transferswitch 15 a and main load panel 15 b and load sub panel 15 c to a homewhich consists of a group of electrical loads consisting of an oven 16,clothes dryer 17, air conditioner 18, selected lights 19 and selectedmiscellaneous load items 20. It is noted that the load 19 labeled lightsis intended to represent high priority loads which are desired to alwaysbe connected to the power source including for example security lights,high priority lights, food storage appliances such as freezers andrefrigerators, various alarms including intrusion and fire alarms, etc.A generator and transfer switch controller 14 is responsive to the gridpower to control the setting of the transfer switch 15 a to selecteither grid power 12 or generator power 13 to power the home, and tostart and stop the generator 13 as needed. As is conventional in theart, transfer switch 15 a is a break before make switch to prevent itfrom simultaneously connecting both inputs (on the left) to the output(on the right) while switching and is shown with a dashed lineconnecting the moving portion, which will be referred to herein as theswinger, to communicate with 14 to indicate that the switch iscontrolled by 14. Practical devices called transfer switches incorporateboth 15 a and 14, and sometimes 15 b and/or 15 c in a single metalenclosure. It is noted that FIG. 2 is a simplification for purposes ofexplanation of operation and one of ordinary skill will know that inpractice prior art transfer switch 15 a, panels 15 b and 15 c and thecontrolling mechanism will be much more elaborate and may incorporatesolenoids, relays and multiple sets of contacts as well as mechanicalsafety and lockout features.

While FIG. 2 shows a direct connection from the power grid 12 to thetransfer switch 15 a, it is common that that connection is taken fromthe main panel 15 b which will include a power meter, circuit breakersand possibly other circuitry. Typical maximum service ratings for homesare set by the size of the wiring from the grid to the home andtypically rated at 100, 200 or 400 amps depending on the size of thehome. Similarly, the generator connection via the transfer switch 15 aand sub panel 15 c will have a maximum rating, and the generator has acircuit breaker to prevent the total of the loads being powered fromexceeding that maximum rating. Typical maximum ratings for backupgenerators are often substantially less than the service rating for thegrid connection. To prevent the generator from being overloaded backupsystems often include the distribution sub panel 15 c and only highpriority and low current loads such as 19 and 20 which are neededwhenever the power is lost and whether the home is occupied or not areconnected to that sub panel and powered by the backup generator. Therest of the high current loads which the generator is not capable ofpowering are connected to the main panel 15 b and remain unpowered whilethe grid power is off and the backup generator is running. Whiletransfer switch 15 a, main panel 15 b and sub panel 15 c areindividually shown in FIG. 2, for purposes of simplifying thedescriptions below main panel 15 b and sub panel 15 c will not be shownand the transfer switch will be labeled as 15. One of ordinary skillwill know that one or more distribution panel will be required for thesystems described, even though they are not shown in the drawings.

Power grid is used herein in its common and ordinary meaning and refersto any commonly known and used sources of electrical power to homes andbusinesses, e.g. public and private electric utility companies. Whilesuch companies normally are part of a continent wide interconnection ofpower companies, that does not need to be the case. Further, while thepreferred embodiment of the invention described herein with respect to asystem having a power grid connection, it may also be practiced withonly one power source such as generator 13, or with a plurality of powersources with none of them being a power grid. Such embodiments will findparticular use where no power grid is available or is not desired to beused such as in transportation vehicles, mobile or remotely locatedapplications.

Electrical device (or load) names oven, clothes dryer, air conditionerand lights are used in their common and ordinary meaning e.g.electrically powered devices found in the home. The miscellaneouselectrically powered devices (or loads) found in the home, include butare not limited to entertainment devices, appliances and other modern,electrically powered conveniences. It will be understood that loaddevices are used herein by way of example and it will be understood byone of ordinary skill that the inventive teachings herein will apply toother devices as well.

Generator 13 usually includes a rotating power source, typically aninternal combustion engine powered by a liquid or gaseous fuel, or aturbine powered by steam or water power, an electric motor powered bystorage batteries, a flywheel powered by stored energy, a hydraulicmotor powered by a compressed gas or a fluid stored with potentialenergy, or numerous other types of rotating power sources which convertmechanically or chemically stored energy to mechanical rotation as isknown to one of ordinary skill. In addition, the rotating power sourceis typically coupled to an AC alternator (as compared to a DC generator)to provide AC power of the same voltage and phase configuration as thatreceived from the power grid. In the U.S. the common power for homes is240 volts single phase and will often be used in the examples of theFigures but it will be understood by one of ordinary skill that theinvention may be utilized with many other power configurations.

The transfer switch 15 and the generator and transfer switch controller14 are also somewhat simply referred to in these teachings. The transferswitch transfers power from the generator to the loads in the house inplace of the failed grid power. The generator and transfer switchcontroller 14 controls starting and stopping of the generator and theposition of the transfer switch. These elements are divided in thismanner for ease of understanding the prior art and the presentinvention. This usage is somewhat different from the common use of thesenames in the art, wherein transfer switch generally refers to a deviceincorporating the generator and transfer switch control circuitry 14(and often other circuitry) as well as the switch 15 a to transfer theload from one power source to the other. In some instances, such as thepreviously mentioned Generac device, one or more additional switches areincluded to disconnect low priority loads during generator use. For easeof understanding the present invention these are all simply referred toherein as transfer switch numbered 15, and the controls for the switchand generator (and possibly other devices) are numbered 14.

Some backup systems operate to supplement power supplied by the powergrid during heavy peak usage times such as very hot summer afternoonswhen the power grid approaches its maximum capability due to widespreaduse of air conditioning. In these instances, the grid power may still beavailable but the generator is used to power some or all of the houseloads, or the generator power may be synchronized to and paralleled withthe power grid to provide part or all of the power to the house loads.When the house load is very small such paralleled generators may feedpower back into the grid to in effect sell power to the utility companyby causing the power meter to run backwards. These operations require amore complex control, transfer switch and generator operation than shownin FIG. 2. The inventive concepts disclosed herein will also be usefulin such systems. It will be recognized however that in such paralleledsystems when the power grid fails it is important to disconnect thepower grid from the generator in order to prevent damage to thegenerator or possible harm to workers who are repairing the gridfailure.

FIG. 1 shows an abbreviated flow chart of the decision making process ofthe generator and transfer switch controller 14. Processing steps arerepresented by rectangles, input/output steps by parallelograms,conditional or decision steps are represented by diamonds and flowdirections are shown by arrows. Basically, the flow chart operates tostart the generator and move the transfer switch to the generator whenthe grid power fails. The decision making starts at start 1, followed bysensing the grid power 2 to obtain information about the quality of thepower, followed by a decision step 3 to decide if the quality of thegrid power is sufficient (e.g. the power is on and within the range ofexpected voltage). If the power is on a next decision step 4 is enteredto determine if transfer switch 15 is in the position to supply gridpower to the home, if so the decision making returns to 2 and if not thetransfer switch 15 is moved to the grid power position in 6. The loopnormally remains in operation until the grid power goes off causing thetimer off step 5 to be entered from decision 3.

If the grid power remains off for 5 seconds the process continues to thegenerator running decision 7. If the generator is not running it isstarted in 8 and another 5 second delay 10 is entered. At the end of the5 second delay the process returns to the input of 7 to verify that thegenerator is running, if not another start is performed and if thegenerator is then running the process continues to check the transferswitch position in 9. If the transfer switch is in the position toprovide generator power to the house the process returns to 2 tocontinue sensing grid power to see if it has returned to normal, and ifthe transfer switch is not in the position to power the house from thegenerator it is switched in step 11 and then the process returns to waitfor sensing the return of grid power 2.

Compared to an actual prior art device the flow shown in FIG. 1 andaccompanying description above is greatly simplified for convenience ofunderstanding the basic operation of the system of FIG. 2. For example,for simplicity no step to stop the generator is shown, nor is the exitfrom 5 shown if power does not stay off for 5 seconds. Many additionalsteps, checks and considerations are usually found in commerciallyavailable systems to recognize and accommodate the many possible modesof short and long term power failure and to protect the generator. Suchsteps include for example a periodic (e.g. once a week) start andexercise of the generator and transfer switch to improve reliability anda delay in shutting down a generator which has been running in order toallow it to cool down without a load being applied. The timers 5 and 10are greatly simplified and usually involve many other decision makingsubroutines and branches to avoid false starts of the generator duringmomentary power glitches and to allow the generator to attain properspeed, corresponding to proper AC power frequency and voltage, beforeconfirming that it is running.

It will be understood from the description of FIGS. 1 and 2 that whenpower from the power grid is lost, the generator 13 is started and whenit is operational the transfer switch 15 is moved so the power from 13is coupled to the loads 16-20. Importantly, the generator 13 must bedesigned so that it is capable of powering all of those loads when theyare simultaneously turned on, otherwise the generator will be overloadedand its internal circuit breaker will trip. In extreme cases ofoverloading the generator may be damaged before the internal circuitbreaker can trip. Often generators are intentionally designed to onlyprovide power to handle a part of the total load, and the occupants ofthe house must remember not to turn on certain large loads, for examplethe air conditioner and oven, which would cause an overload. Inaddition, if those large loads are on at the time when power is lost,the occupants must quickly turn them off before the generator is startedand transfer switch moved to prevent an overload. This all presents asubstantial possibility of generator damage resulting from human error.

FIG. 3 is a simplified example of an improved prior art version of thebackup system in FIG. 2 which provides power to a group of loads,including a set of uncontrolled loads and a set of controlled loadswhich may be simultaneously switched off if the generator becomesoverloaded. After the controlled loads are simultaneously switched offthey may then be automatically (and blindly) switched on in a sequentialfashion according to priority, each additional load being switched atime period (e.g. 3 minutes) after the previous one. The previouslymentioned Generac Nexus LTS Load Shed system is representative of asystem of this type. FIG. 3 additionally includes load managers 14 awhich are contactors to switch the high current load on and off inresponse to a control signal. A contactor is essentially a high currentrelay which switches the load completely on or off. Contactors may bemechanical with movable parts or solid state with electricallycontrolled switches. The Generac DLM Load Control is a contactor of thistype with a control input which is wired to and controlled by theGenerac Nexus system. If during the reconnection sequence a certainpriority load again overloads the generator (e.g. it is blindly switchedon without knowing if it will again cause an overload), that load andall lower priority loads are disconnected for a period of time (e.g. 30minutes) before the connection is tried again. When grid power isavailable the generator & transfer switch controller 14 operates (viacontrol signal connections shown by arrowed lines) all of the loadmanagers 14 a connect their respective loads.

When the generator is running, the generator & transfer switchcontroller 14 operates to detect that the generator 13 is overloaded (bysensing the frequency of the AC power produced by the generator) andcauses all of the load managers 14 a to simultaneously disconnect theirrespective loads from the generator. Shedding the nonessential circuitswhen the generator is overloaded helps protect the generator of FIG. 3as compared to the system of FIG. 2, however there are shortcomings inthis approach. For example, by detecting the power frequency thegenerator must already be overloaded to the point of not being able tosupply enough rotating torque to the alternator to maintain properspeed. Short term speed variations resulting from momentary loads suchas electric motor starting currents must also be accommodated. Mostgenerators can handle significant excessive output currents for shortperiods of time and that is useful in providing large starting currentsfor motors, for example such as those required for starting airconditioner compressors. These large starting currents normally go awayafter a few seconds when the motor armature and its mechanical load havebeen accelerated to operating speed. Additionally, as will be recognizedfrom the teachings herein, in some circumstances which will be describedmore fully below, it is unnecessary to simultaneously disconnect all ofthe low priority loads or to blindly reconnect them.

Accommodating such momentary high currents is common in the circuitbreaker art, where circuit breakers are designed to trip according to aprogrammed load vs. time curve. For example, a particular 10 amp breakerwill trip with a 12 amp load after 30 seconds, may support a 15 amp loadwithout tripping for 5 seconds, but will trip very quickly with a 20 ampload. Various thermal and magnetic technologies are utilized for suchcircuit breakers. For example, a bimetallic strip may be used to tripwith slightly high currents after those currents have persisted forenough time to cause the strip to heat and bend whereas an electromagnetis used to quickly pull a latch to disconnect for large currents. Agenerator will often have such a circuit breaker installed forprotection. It is important that loads presented to the generator do notexceed the circuit breaker's load vs. time curve causing it to trip.Most such circuit breakers used in backup generators for homes and smallbusinesses have to be manually reset.

The use of AC power frequency detection for control of load shedding isproblematic. If the frequency detection is too sensitive unneededshedding may occur, or if it is not sensitive enough, slow or no loadshedding may occur with the possible result of the generator's circuitbreaker tripping thus removing all power. A one size fits all frequencythreshold used to cause complete disconnect of the load from thegenerator may allow overheating or other damage to the generator 13under some combination of time and load conditions. It is preferred thatthe present invention control of the load shedding be designed toaccommodate varying loads of connected loads, determine if a load can besafely powered before the load is connected and otherwise operate suchthat it prevents an overload from happening, rather than attempting todetect and cure the overload after it has happened.

Another problem occurs when the transfer switch first switches from thepower grid to the generator with too many loads connected. A similarcondition exists when a connected load instantly or quickly increasesits individual load causing the total generator load to exceed thegenerator's capability. In such situations if the generator has beensized such that it can not simultaneously power all of the loads whichare connected, it will immediately go into overload. Depending on howfast the detection of the condition and disconnect of the loads takesthe overload condition can continue for several seconds, or possiblyeven minutes. Most generators are designed to accept an instant 0 to100% of its rated load change without damage (although not withoutserious speed and voltage fluctuations), however they may not bedesigned to accept an instant 0 to overload condition change which canhappen when switching from grid to generator power, or a partial tooverload condition which can happen when a connected load suddenlychanges. Such overload conditions may damage the generator or, as withany closed loop system, cause the generator to become unstable, possiblyeven going into speed and/or power output oscillations if properlinearity and/or damping does not exist to make the loop stable for thatoverload condition.

The following FIGS. 4-23 are simplified diagrams given by way of exampleto enable one of ordinary skill to understand and practice the inventionin small backup power systems, defined herein as those used for anindividual home or business with a single or multiple phase serviceconnection of 440 volts or less and single meter service connection of400 amps or less, or with separately metered normal and a time ofservice connections which total 800 amps or less. It is often desirableto utilize a backup generator which is only capable of providing powerfor part of the maximum possible load which can be presented. In respectto FIGS. 4-23 the following brief descriptions will be useful. Moredetailed descriptions of these and other elements will be understoodfrom the teachings below.

Environmental, User & Misc. Devices 21. User interface, e.g. an iPad orcomputer type display with interactive software, Environmental Sensorse.g. for home & outdoor such as temperature, sunlight, humidity, wind,generator operating conditions, Misc. Devices e.g. vehicle and batterysensors (e.g. usage time and distances, charge, temperature) appliancesensors (e.g. wine cooler, freezer and oven temperature), vehiclebattery charger and battery, communications (e.g. telephone, internet,wireless, alarm), motion sensors to detect when areas of the property,particular rooms, or the home are vacant or occupied.

Power Source Monitor 49 and load control processor 25 b. The PowerSource Monitor is preferred to be a separate module because of its needto monitor the power source(s) outside the home but may be part of theload control processor. The Power Source Monitor may be installed at thebackup power source and monitors its operating parameters and conditionswhich may affect its operation, for example such as ambient temperature.The load control processor is the computing unit of the system and maybe part of the user interface (e.g. iPad) which is preferred to belocated in the home but may also be part of other equipment. The loadcontrol processor receives information about the various components ofthe system, receives user input, inputs from various monitors andsensors (including a time clock) and controls the Transfer Switch,Generator and Loads according to various pre-programmed parameters andthose inputs.

Load Modules 43, 22 b, 22 c. Modules which communicate with the loadcontrol processor and which may provide information about the load, theload's environment and/or operate to permit control of the load. LoadModules include Load Limit Modules and Load Switch Modules.

Load Limit Module 43. Load limit modules limit the load presented byvarious devices by e.g. current limiting, power factor adjustment and/ortime modulation of current. Load Limit Modules may include loadcondition sensors such as voltage, current and power factor sensors andthe type of load operation for communication to the load controlprocessor.

Load Switch Module 22 b, 22 c. Load Switch Modules switch power to loadson and off. Load Switch Modules may include load condition sensors suchas current sensors and the type of load operation for communication tothe load control processor.

Controllable Load(s) 48. These are loads which may be controlleddirectly without the need for a Load Module. Examples includeelectronically controlled devices such as heating and air conditioningsystems, vehicle battery chargers, light dimmers & remotely controlledlights and internet and wirelessly controlled appliances.

Communications between the various system components 27, 28, 45, 46 maybe wired or wireless. For ease of installation are preferred to be viabidirectional wireless data links, for example such as via IEEE Std.802.1X. For those elements which communicate in one direction theassociated receiver or transmitter circuitry may be omitted.

It will be understood that many elements that are necessary for anactual system have been omitted as they will be readily known to theperson of ordinary skill from the present teachings. Additionally, manyinventive features and elements which are described with respect to oneFigure will not be shown in another Figure but it will be recognizedfrom the teachings herein that such omitted features and elements maystill be incorporated.

FIG. 4 shows a simplified diagram of the preferred embodiment of theinvention in which the power grid 12 or a generator 13 may power a groupof loads including set of uncontrolled loads and a set of individuallyswitched loads. The invention may be utilized with the power grid alone,the generator alone, both, or with the generator serving as a backupduring power grid failure. Heretofore overloads of the power gridservice has typically been addressed by making the service, transferswitch and distribution panel(s) large enough to handle the maximum loadthat can occur. While that approach works well it is neverthelessexpensive due to increased equipment costs and may become unworkable inthe future. For consumers wishing to purchase electric and hybridvehicles, having to upgrade their existing electric service toaccommodate one or two vehicles and their associated high currentchargers operating at the same time is an additional and costlyconsideration for such a purchase. In some instances, the public utilitymay not be able to provide enough power via the existing grid to upgradeexisting service and provide new service to everyone desiring suchcapability. Accordingly, while using large service connections hasworked well in the past, with the demand created by electric and hybridvehicles the utility may not allow larger capability service whicheffectively prevents overload from being used.

As an example, consider a family that wishes to purchase two newelectric vehicles of the kind that could each use a 90 amp 240 voltcharger circuit. If both drivers work during the day and wish to chargetheir vehicles when they come home from work that presents a substantialload to the electric service. Two of these circuits added to an existing100 amp service would trip the service breaker if both chargers weresimultaneously used. If only one charger was used any other high powerload such as an electric stove or oven or air conditioner would trip theservice breaker. Similar problems would exist for a 200 amp service.Upgrading to a 400 amp service would be costly, and might not even bepossible if the utility company does not have an adequate transformerand grid wiring to the house. The present invention will operate tointelligently manage the loads and prevent tripping the service breakerwhile at the same time allowing the family to set priorities for the useof power that can be safely delivered.

It is desired that the invention operates to ensure that the loads arecontrolled so that they do not overload the power grid serviceconnection when power is provided by the power grid, or overload thegenerator when power is provided by the generator. One of the inventivefeatures of the invention is that it may be determined whether or not anoverload will occur, or is likely to occur at the time of connection orsubsequently during that connection, before a load is connected. Theinventive features of the preferred embodiment are described hereinprimarily in respect to preventing overloads of the generator 13 but itwill be understood from these teachings that the invention may operateas well to prevent overloads to the power grid service connection. Thisfeature of the invention will not only reduce possible damage or circuitbreaker tripping during generator operation but will also reducepossible damage or circuit breaker tripping during power grid operation.

FIG. 4 has the same power grid 12, generator 13, transfer switch 15 andloads 16-20 as with FIGS. 2 and 3. Generator and transfer switchcontroller 14 is not shown in FIG. 4 for simplicity, however it ispreferred that load control 25 a communicates with either the 14 or 15in order to verify the position of the transfer switch. In addition,FIG. 4 shows load monitor 23 a to monitor the load on the generator(which is also the power supplied by the generator) and the timely poweroutput from the generator is conveyed to load monitor 25 a via generatormonitor 24. Load monitor 23 a also provides timely power output from(e.g. provided via) the service connection and thus the load on thepower grid, when the transfer switch is in the power grid position. Inthat the invention finds applicability for preventing overloads it willbe understood that it may be utilized for any power source orcombination of sources, including off grid systems such as remoteterrestrial, aircraft, on and off road vehicles and marine applicationswith or without connection to the power grid.

It is preferred that the timely power output is an instantaneous measureof the current provided by the generator. Because most generatorsincorporate voltage sensing and correction circuitry, often by way ofcontrolling the power applied to the exciter winding in the alternator,the output voltage is maintained nearly constant. Of course, the voltage(and power factor if desired) may be measured and utilized as well. Byknowing the output voltage of the generator is being held to a constantvalue, for example 240 volts in a single phase output, by measuring orsensing the instantaneous current flowing from the generator, aninstantaneous measure of the output power may be had. It may also bedesirable to utilize a measure which is not instantaneous. Examples ofsome non instantaneous measures include an average over time, a timerelated measure of output power, a measurement with reduced noise, anapproximation of the average load provided to the generator, to providea measure of the resulting heating of the alternator or engine, toprovide a measure of fuel consumption by the generator, to provide ameasure of the power consumption by the load(s).

A generator monitor 24 which receives data from load monitor 23 a andcommunicates that load information to a load control 25 a viacommunications link 28 a. It is noted that load monitor 23 a may belocated in the circuit input to (to the left of) the transfer switch 15in order to monitor the load only when power is provided by thegenerator. Monitoring the output of the transfer switch is preferrede.g. it is useful for characterizing load parameters e.g. current orwattage consumption, as individual loads are turned on and off (or turnon and off on their own) at any time, and for controlling the loadpresented to the grid so as not to exceed the service connectioncapability as will be explained below.

FIG. 4 also shows load switch 22 a is responsive to load control 25 avia communications link 26 a and operable to connect and disconnect oven16 from power coming from the transfer switch, load switch 22 b viacommunications link 26 b is operative to connect and disconnect theclothes dryer 17 and load switch 22 c via communications link 26 c isoperative to connect and disconnect the air conditioner 18. It will beunderstood from the teachings of the present invention that one or moreload switch 22 may be removed (for controllable devices or high prioritydevices as described herein) or replaced with a load control 43 or othertypes of control devices as will be described in more detail withrespect to FIGS. 6-9. While load switches 22 have been described asbeing responsive to load control 25 a, it will be preferred that theyalso include bidirectional communications capability in order that loadcontrol 25 a may determine and/or verify the state of the switch (e.g.open, closed, dropped or other information) and further it is preferredthat the switch include other functions as will be discussed below. Inaddition, it will be understood that load switches may be operatedwithout a separate load control 25 a, as that function may beincorporated within the load switch 22 (or load limit 23).

As used herein, communications and communications link are meant toencompass the conveyance of information from one point to another by oneor a plurality of electronic circuits and may be the same or differentfor each type of information and each type of connection as desired. Thecommunications links may be of any type suitable for communicating theparticular information desired over the desired distance at an adequatespeed and resolution with necessary reliability and may be continuous ornot in order to fit a particular application of the invention. Theinformation may be in, and may be communicated in, any suitable form, orforms e.g. analog, digital, optical, magnetic, electromagnetic waves,wired or wireless and may be communicated in single direction,bidirectional, singular or redundant form, and the communication may usehandshaking, networking or broadcasting, may be multiplexed in anyfashion, networked, daisy chained, point to point or otherwise asdesired to fit a particular embodiment of the invention. For example, ifwired communications links are desired, RS-232, IEEE 1901 or USB may beused or for wireless ZigBee, IEEE 802.1X, Bluetooth, or Wi-Fi may beused, all being well known to one of ordinary skill. The communicationsmay be simply contained within a dedicated implementation of theinvention or may utilize a network covering a larger area forcommunications, for example via the internet. The invention describedherein and/or its communications circuits may be shared or included inother systems and devices such as for example a home control system.Communications theory is a broad but well known field of art readilyavailable to one of ordinary skill wishing to practice the invention,accordingly the communications links will not be discussed extensivelyherein.

Communications between the load control 25 a and load switches 22 a-22 c(or load control 43 described below) are provided by communicationslinks 26 a, 26 b and 26 c respectively. In addition, communicationsbetween load monitor 23 a and generator monitor 24 is provided bycommunications link 27 b. Communications between generator monitor 24and load control 25 a is provided by communications link 28 a.Additionally optional communications link 27 a may be provided betweengenerator 13 and generator monitor 24, and additional communications maybe provided by optional communications link 28 b between generatormonitor 24 and load control 25 a. These communications links arepreferred to be utilized to provide generator monitor 24 and loadcontrol 25 a with, inter alia, additional information about theoperation of generator 13 and to communicate back to generator 13 andgenerator monitor 24. Various parameters of the connected devices may becommunicated to load control 25 a as well.

Many prior art generator systems incorporate digital engine andalternator control systems which incorporate monitoring of theperformance of the generator. Such monitoring includes determining theengine and alternator temperature, engine overload, voltage output, RPM,AC power frequency, current and power output for each leg of thealternator, total current output from the alternator, power factor, andpercent of true total available power being supplied to the load. Thesecontrol systems often further include over current warning, underfrequency warning and overload warning (by measure of current and/orfrequency). In many systems it is desirable to communicate with thesecontrol systems to provide some or all of the monitoring information anddevice parameters to the load control 15 for use in its load connectionand other decision making. A load shed signal, responsive to a lowfrequency or over current condition or both, indicates the generator isoverloaded, is also available on some systems. Assuming adequateinformation about the operation of the generator is available directlyfrom the engine and alternator control systems, that information may becoupled directly to load control 25 a via a communications link (notshown) making load monitor 23 a, generator monitor 24 and theircommunications links redundant in respect to monitoring the generator sothat they may be eliminated in that respect. Load monitor 23 a is stilldesirable for use to characterize loads and for timely monitoring of theload presented to the power grid, which is also the timely power outputfrom the service connection, as previously discussed. In the instancewhere the power grid output is desired, 23 a may be located at any pointon the power grid circuit, such as the input or output of the transferswitch 15.

It is preferred that load control 25 a operate to provide power, eitherdirectly or indirectly e.g. via generator monitor 24, to all of thedevices to which it is connected for purposes of communications and/orsensing operation. It is also preferred that load control 25 a (as wellas the devices with which it communicates wirelessly) include its ownbackup power source, such as a rechargeable battery, in order that itand the devices with which it communicates may continue to operatewithout interruption whenever its primary power source fails such asduring the time interval between the failure of power from the powergrid and the supply of power backup power from the generator. Of course,for wireless communication links it is preferable that the variouswireless devices have their own power source(s), including backup if thedevice is critical to operation during outages of that source.

One or more optional additional communication link(s) shown in FIG. 4 by28 c, may be provided between load control 25 a and other optionaldevices such as sensors, information sources, displays, feedback, etc.shown as environmental, user and misc, devices 21. The display andfeedback elements used in respect to the user may be combined ifdesired, for example such as with a touchscreen. These devices caninclude various sensors, for example such as temperature sensors tomonitor outside temperature useful in controlling air conditioneroperation, engine or alternator cooling air inlet or exhaust temperatureuseful in determining genset load, refrigerator or freezer temperatureto determine if additional cooling is needed. The sensors for examplemay be utilized by 25 a in the setting of priorities for loads to beconnected to the generator. Such devices are desired to communicate withthe load control as will be described further by way of example below.

Sensors and other components suitable for interface with the processorof 25 and/or use in practicing the invention are available from AnalogDevices of Norwood Mass., Texas Instruments of Dallas Tex., NationalSemiconductor of Santa Clara, Calif., Sensirion of Westlake Village,Calif. and many other suppliers as will be known to the person ofordinary skill in the art from the present teachings. Additionally, theload control of the invention herein may communicate with other devicesor services within or outside of the home area such as via telephone,internet, long distance wireless and the like e.g. in order to provideand receive information as well as handle and generate requestsregarding power consumption, the devices which are connected, availablefor connection and the like, as will be described in more detail below.

Generally, the communications links which are considered desirable topractice the preferred embodiment (i.e. the best mode) of the inventionare shown in FIGS. 4 and 5 with solid lines with solid arrows showingthe primary direction of communications. For example, the loadinformation from load monitor 23 a is communicated to load control 25 aby communications link 27 b which is shown in a solid line with a solidarrow. Additional communications which may be desirable to practiceadvanced features of the invention are shown with dashed lines andarrows, for example the environmental, user and miscellaneous devices 21communicating with load control 25 a.

Load switches 22 a-22 c are preferred to be of a latching, dropout typewhich will automatically open circuit when power to the load switch(from transfer switch 15) is lost and thereafter and must besubsequently directed to close their circuit (after generator power isavailable via transfer switch 15) to provide power to the load.Accordingly, when power from the power grid is lost the load switches 22a-22 c will switch to open circuit and remain in that state until theyare closed by load control 25 a thus preventing a generator overloadwhen the transfer switch selects the generator output. Other switchtypes, or load control circuits, e.g. such as 43, or load controls,discussed below, may be utilized as well as will be known to person ofordinary skill from the teachings herein. Additionally, while the loadswitches 22 a-22 c and load control 43 below are shown as separate unitsthey may be combined with, or incorporated in the transfer switch or itscontrol or in particular loads. The parts or all of the invention arealso suitable for being combined with or incorporated in the generator,and may also include transfer switch control and/or transfer switch aswill be known to one of ordinary skill from the teachings herein.

After a grid power loss, the generator 13 will be started and transferswitch 15 will be switched to couple generator power to the house undercontrol of the generator and transfer switch controller 14 (not shown inFIG. 4). At this time load monitor 23 a will operate to measure theelectrical load presented to the generator by the house, which at thispoint of this explanation is the load presented by the lights 19 andmiscellaneous loads 20 since load switches 22 a-22 c are preferred tohave switched, and remain open when grid power was lost and thereafteruntil turned on. Accordingly, 23 a provides the timely power output ofthe generator.

Because the voltage out of the generator is known, for example 240volts, the load monitor 23 a may simply be a current sense coil,inductor, transformer, sensor or integrated circuit which provides ananalog voltage output that is proportional to the electrical currentsupplied to the loads by the generator. Rogowski coils such as thatdescribed in U.S. Pat. No. 6,313,623 to Kojovic et al. are particularlyuseful in that they can respond to fast changing currents and are notprone to saturation as are iron core transformers and coils and arereasonably immune to electromagnetic interference. The output of 23 a iscoupled to generator monitor 24 where it is preferred to be converted todigital with the digital value of the current being coupled to loadcontrol 25 a via communications channel 28 a. Various other types ofknown load monitors are readily available and may be utilized andcoupled to load control 25 a as will be apparent to one of ordinaryskill from the teachings herein.

As previously described, load (and other generator) information may betaken directly from the generator. For example, the aforementionedCummins model GGHE generator includes their PowerCommand control modulewhich provides a wealth of information about the operation of the engineand alternator over RS-232 and other communications links. Many othergenerator manufacturers provide similar modules and functionality. Itshould be kept in mind however that the information provided by thesemodules may not always be accurate due to cost savings and tolerances.For example, an overload indication may respond only to electric poweroutput but not measure engine or alternator temperature. If thegenerator is operated at significant altitude, or on a hot and humidday, the cooling system may not be able to prevent an over temperaturetype of overload from occurring even though the power output isotherwise below that which would generate an overload signal.Accordingly, it is desirable that load control 25 a be capable ofsensing several parameters of the generator, and that it may beprogrammed or otherwise set to operate in response to those parametersand the particular generator and environment.

Load Monitor 23 a may be used to determine the actual kilowatt output bymeasuring both voltage and current and may also be used to determine thepower factor (the ratio of active power to the arithmetic apparentpower) of power being supplied to the load. Calculations may beperformed in load monitor 23 a, or generator monitor 24 or load control25 a as desired, however in this example it is preferred that 23 a senseactive and apparent power by sensing or measuring the present voltageand current in real time (or near real time), transmit those values togenerator monitor 24 in real time (or near real time) where they areconverted to digital in near real time with the digital values beingcommunicated to load control 25 a in near real time where thecalculations of power factor and load are performed. By using real timeor near real time values of voltage and current the relative phase ofthe two is preserved and that phase information can be used in thecalculations to timely determine the power output of the generator whichis used to determine the available power for other loads. As usedherein, timely will be used to mean instant, real time, close to realtime or a suitable time. In particular timely voltage, current, wattage,power or other quantity or parameter will mean the quantity of, or valuerepresenting the quantity of, the parameter existing at a time which issuitable to be useful in the operation of the invention. For example,timely voltage output or power output values may be measured andtransmitted to the load control with some time delay which delay is notlong enough to impair the proper operation of the load control.

For this explanation, load control 25 a will be assumed to know at leastone maximum output power parameter e.g. maximum wattage or current ofgenerator 13 (or a plurality of parameters e.g. its maximum outputcurrent vs. time capability). The maximum output power parameter iscompared against the actual output at the time as measured by 23 a andthe remaining available power at the time is then calculated. Otherparameters may be utilized to determine the projected power available ata future time or over a future time period may also be calculated. It isalso desired that the power parameters e.g. initial current requirementsand current vs. time curve(s) of each load 16-18 are known to the loadcontrol 25 a. It is desired that each of the loads 16-18 has associatedwith it one or more known priority parameter(s). As used herein, knowand known mean to have been previously stored in a memory and availablee.g. having been previously manufactured with, programmed with ormeasured. All such parameters are preferred to be manually orautomatically changeable as will be described below. In reality it maybe that one or more parameters is not know at the time and must bedetermined or estimated as will be described further below.

After generator power is made available via the transfer switch, loadcontrol 25 a operates to determine if the highest priority load 16-18can be supported by the available power of generator 13 and if so loadcontrol 25 a causes the load switch associated with that load to beclosed via commands conveyed to the switch by its correspondingcommunications channel. Next load control 25 a operates in response tothe new power measurement from 23 a to determine if the next highestpriority load 16-18 can be supported by the available power from thegenerator. If so that load is connected by command sent via its switch'scorresponding communications channel. Likewise, the third priority loadrequirement (in this case the last load of the three) is checked againstavailable generator power and the load connected if sufficient poweravailable. While only three controlled loads are shown in FIG. 4, itwill be known from the present teachings that the number of loads whichmay be controlled is not so limited and additional controlled loads andcorresponding communication links (e.g. 26 d-26N) may be utilized. Inthe event one or more of the loads cannot be connected because ofinsufficient available power from the generator, the load control 25 awill periodically compare the available power supplied by the generatorto the power required by the load and if possible connect the load. Itmay be that available power for a load results from one or morepreviously connected loads no longer requiring power, for example theclothes dryer is finished and that load may be disconnected to preventit from being turned on and creating an overload. Or, the airconditioner may require less power to run because outside air has cooledand that additional information may be utilized by load control 25 a todetermine it is safe to connect another load.

Load control 25 a is preferred to operate in substantially continuousmode to constantly compute load requirements and generator capabilitiesto connect and disconnect loads according to priorities as a result ofchanging loads and priorities. Lower priority loads may be disconnectedto accommodate higher priority loads. Environmental, user and otherparameters may be utilized by load control 25 in order to determine thatit is safe (or that there is a high probability that it is safe) toconnect a particular load. It is preferred that load control 25 a ensurethat loads such as air conditioners which should not be cycled tooquickly remain disconnected and/or remain connected for appropriateamounts of time. Load control 25 a also monitors the generator 13 foroverloads, and other parameters such as minor equipment failures such asslight overheating and chooses which loads to disconnect, or in theevent of a significant failure may change the transfer switch 15 back tothe grid power position (even though there is no grid power). Of course,load control 25 a will monitor grid power and change the transfer switch15 back to the grid power position when power returns, meets expectedparameters and is expected to continue meeting those parameters. It ispreferred that after the transfer switch returns to grid power thatloads are reconnected one at a time in order to prevent a largeinstantaneous power demand surge.

Although continuous operation is preferred, the invention may bepracticed with other types of operation as well, especially when powerconsumption of the load control is intended to be kept to a minimum. Itmay be operated at periodic intervals or may be caused to operate onlywhen one or more parameter of the system changes appreciably. In onealternative, load control 25 a may operate in a low power standby mode,only checking for the presence of power from power grid 12 and remain instandby as long as grid power is present, but change to a more active orfully active mode if grid power experiences problems such a fluctuationsin voltage or frequency (outside of expected parameters), or failure.

It will be appreciated from these teachings that load changes on thegenerator 13 may occur during operation because the switched loads 16-18(if connected) or the unswitched loads 19 and 20 may change, and thosechanges may be communicated by the generator monitor 24 via 27 b orotherwise to provide data via generator monitor 24 to load control 25 awhich may use this data to characterize and store load characteristics.For example, if a request is made of load control 25 a to turn onclothes dryer 17 via load switch 22 b, the change in current sensed byload monitor 27 b over the next few minutes can be stored and used assome of the parameters, e.g. starting and current after initial warm up,for that load. In this fashion unknown parameters may be determined orestimated and known parameters may be updated. While this type ofmeasurement might be interfered with by other loads changing, if severalconsistent measurements and some inconsistent measurements are made fora number of dryer requests, it is probable that the consistentmeasurements are reasonably accurate. The consistent and inconsistentmeasurements may be determined by correlation or other statisticalmatching techniques. The consistent measurements may then be averaged toremove small variations due to dryer load, ambient temperature and othersuch changes. Of course, more accurate measurements may be made bydirectly monitoring the dryer load as will be discussed below.

FIG. 5 shows a more detailed diagram of load control 25 a. Communicationlinks provide for communications between a processor circuit 33 a andvarious devices as discussed herein. Load control 25 a containsinterface circuits 29 a-29 h to interface communications channels 28 a,28 b (optional), 30, 31, 32 and 26 a-26N to a processor circuit 33 a.

The processor circuit will include a processor, e.g. a digital machineperforming logic, computing and/or program execution operations whichmachine accepts data and runs (i.e. executes) logic operations,computing operations and/or program steps to produce results. Theprocessor circuit will also include supporting circuitry to facilitatethe processor accepting data, executing one or more logic operations,computing operations and/or program(s), produce and utilize thenecessary results and communicate with other components and devices. Theprocessor circuit and its various elements may be of any of the typessuitable for performing the various desired ones of control, monitoring,storage, communications, calculation and decision making operationsdescribed herein which are necessary to implement a particular versionof the invention. The processor circuit may be implemented with anytype(s) of circuit devices currently known or which will become to beknown in the electronic control systems art including but not limited toanalog and digital circuits, LSI, VLSI, ASIC, PLD, CPLD, FPGA, DSP, IPCore, Array, microcontroller, microprocessor, Multicomputer, RISC or CPUintegrated circuits.

Processor circuit 33 a may also include one or more interface circuitssimilar to 29 (thus eliminating one or more interface circuits 29 whichare external to 33 a). A particular processor circuit may be chosen foruse in implementing the present invention by one of ordinary skill fromthe teachings herein in view of other considerations as well, e.g. powerconsumption, cost, complexity, ease of use, speed of operation andflexibility of operation. Examples of such computer circuits include PCsusing Windows, Linux or other operating systems, Apple products such asiPhone, iPad, iPod, Android product such as the Asus Eee Pad tablet,various RISC, parallel microcomputer and embedded devices. While theprocessor circuit 33 a has been described in the singular, it may beimplemented by multiple circuits or devices as desired.

Communications links 26 a-26N, 28 a and 28 b operate as describedpreviously and in further detail below. Communication links 30, 31 and32 (in FIG. 4 as part of 28 c) communicate with one or moreenvironmental, user and miscellaneous devices (shown in FIG. 4 as partof 21). Communication link 30 is used to supply data from a user inputmodule(s) to processor circuit 33 a of load control 25 a and if desiredcommunication link 31 operates to supply data from the processor circuit33 a of load control 25 a to the same or different user module(s). It isof course possible that such data may be supplied by a singlebidirectional communications link as indicated by the dashed arrow on 30and 31. Data to and from other auxiliary devices may be communicated toand from processor circuit 33 a of load control 25 a by one or morecommunications link(s) 32 as will be discussed further below. Processorcircuit 33 a communicates via communications links 26 a-26N tocommunicate with load switches or replacement devices 1-N respectivelyto cause loads to be connected to the power source (via transfer switch15) and if desired to receive data from one or more load switches orreplacement devices. It will be understood that the preferred embodimentof FIGS. 4 and 5 may utilize a particular processor circuit 33 a, forexample the Asus Eee Pad tablet wherein various other elements of FIGS.4 and 5 are provided by 33 a. In the present example all of the userinputs and feedback devices are preferred to be provided by the Asus EeePad touch screen and communications links 26 a-26N, 28 a, 28 b and 32being provided via its IEEE 802.11 and/or Bluetooth wirelesscommunications capability.

As a simplified example to aid in understanding the operation of theload monitor and load control of the preferred embodiment, consider agenerator which because of its existing load and internal temperaturecan provide 30 amps for up to 5 seconds and 20 amps for 5 minutes and 18amps after 10 minutes. Now consider an air conditioner which requires 30amps for 4 seconds to start, 20 amps to run after that for 1 minute andthen increasing to 21 amps as the condenser coil heats thereby causingthe head pressure and compressor current to increase. Starting the airconditioner and running it for 1 minute would be possible withoutoverloading the generator. After 1 minute the condenser coil heats andthe air conditioner would overload the generator by 1 amp anddisconnecting it would be advisable. After 10 minutes the generatorwould be overloaded by 3 amps and would need to be disconnected becauseof the substantial overload of the generator. It is desirable that theload control also keep track of the operating characteristics of theother loads which are connected. By knowing the characteristics of thegenerator and load(s), the load control can make a decision of whetherto connect the load, which in this example would not be advisable.

As a further example, add to the above example an ambient temperaturemonitor to provide an environmental parameter. Assume the load control25 a records a decrease of the ambient temperature due to cold rainfallwith the internal temperature of the generator decreasing for a givenload which in turn will allow a somewhat larger load to be accommodated.As used in this context records means to store a plurality of values ofthe same changing parameter, in this instance temperature, over a timeperiod. The rainfall may also be sensed and recorded, For the airconditioner compressor a decreasing ambient temperature will lead to areduced condenser coil temperature, decreased compressor head pressureand decreased compressor current draw. In this instance, depending onthe rate of temperature drop, the expected increase of generatorcapacity and expected decrease of compressor current, it may be possibleto predict that the air conditioner may be safely connected to thegenerator.

Adding a further environmental parameter to the example, it is likelythat humidity will increase due to the rain and the higher humidity airwill decrease the maximum torque output of the generator's motor. Thisadditional environmental parameter may be sensed and recorded forutilization by the load control 25 a in determining the maximum outputpower which will be available in the near future. Because humidity alsoaffects the cooling of the condenser coil by airflow across the coil,this may be taken into account by load control 25 a as well. It will beunderstood that timely determinations of generator maximum output poweras well as load power consumption for a given load may be made by usingvarious environmental parameters. It will be further understood thatdeterminations of upcoming generator maximum output power as well asupcoming load power consumption for a given load may be made by usingvarious changing environmental parameters, upcoming meaning over atleast the next hour unless otherwise specified.

To continue the above example, consider the same generator capability asabove, i.e. 30 amps for up to 5 seconds and 20 amps for 5 minutes and 18amps after 10 minutes. Consider a different load, an oven which willdraw 25 amps for 5 seconds, 20 amps decreasing to 15 amps over 3 minutesand 15 amps intermittently thereafter as the oven thermostat switchesthe heating element on and off. This load can be safely connected to thegenerator since it will not exceed the generator's capacity at any time.

Of course, in the above examples it is assumed that when a connection tothe air conditioner or the oven is made that device will be in operationand will immediately begin loading the generator. It would be useful toknow if each device would in fact be in operation or could be inoperation at some time after connection. As an added factor in thedecision making it would be useful to input the status of the device(e.g. on or off as a parameter), or otherwise determine the likelihoodthat the device would present a load if connected. This considerationrelates to establishing a priority for a load, for example if the ovenor the air conditioner is turned off then it would not present asignificant load if it is connected. If the indoor or outdoor airtemperature were low it is unlikely the air conditioner would present aload if connected. If the oven were operating before loss of grid powerthe thermostat will likely power the heating element when the oven isconnected or within a few minutes thereafter. It is desirable for loadcontrol 25 a to record and use these parameters in its load connectiondecision making.

As a further example of the operation of the load control 25 a considerthe priority of the loads. If the time of day (sunset) is after thenormal time that dinner is prepared in the oven then the oven has arelatively low priority. If the temperature in the house is hot, the airconditioner has a high priority. If generator capacity is available theair conditioner would be connected instead of the oven. On the otherhand, if the oven is in use when the grid power fails it is reasonableto assume food is being prepared. The interruption of power while foodis being prepared can cause a serious problem for the occupants of thehouse making the oven a very high priority load. If the insidetemperature of the house is at a reasonably comfortable level, and ifgenerator capacity is available the oven would be connected instead ofthe air conditioner. The oven use likely will end within an hour or twoand at that time it may be possible to connect the air conditioner,meanwhile the inside temperature of the house will likely not rise touncomfortable levels. It is thus preferred that load control 25 ainclude a real time clock and calendar feature, coupled with calendarfactors such as sunrise and sunset, identification of local temperaturenorms, highs and lows for each calendar day and other information suchas load usage habits, as will be useful in managing generator operationand loads.

If the oven was operating in a self cleaning mode instead of foodpreparation mode when grid power failed as detected by steady and higherthen normal current draw. It is preferred that the oven current draw berecorded via the load control 25 a and used to determine that the ovenwas in cleaning mode. That determination is preferred to be incorporatedinto the assignment of priority to reconnecting the oven. Since ovencleaning is not as important as preparing food, that cleaning can bedelayed while other higher priority loads such as the air conditionerare connected. Of course, it will be desirable to allow the occupants ofthe house to make the decision as to applying power to the oven or theair conditioner as will be explained further below. A temperaturesensor, part of 21, may be provided for a refrigerator or freezer andthat temperature is used in determining the priority of connecting theassociated load. For example, if the freezer temperature is well belowthe safe limit the freezer would be determined to be a low priority loadwhereas if the temperature rises to be near the safe limit the freezerwould be determined to be higher or high priority load.

Secondary factors, such as the time of day and decreasing ambienttemperature of the above example are also preferred to be taken intoaccount in deciding to connect a particular device to or disconnect itfrom the power source. Such factors include, but are not limited to,calendar data, load usage habits, one or more parameter of the load forthe particular device e.g. maximum possible load, expected load forcurrent conditions, projected changes in the load with time orconditions, starting and surge currents (e.g. the starting current of anelectric motor), power factor of the load such as resistive, capacitiveor inductive type loads, the probability that a load will need to beconnected or disconnected during the near and distant future, damagedone by failing to connect a load or by disconnecting a load onceconnected. The short and long term ability of the power source to supplypower in known or projected amounts, environmental factors such asambient temperature, humidity, altitude, quantity of fuel available,fuel delivery rate, quality of fuel, cost of fuel, cost of supplyingpower from a given power source vs. cost of purchasing or supplyingpower from another power source and environmental effects of supplyingpower from a given power source.

In order to evaluate various factors and parameters used by the loadcontrol 25 a for decisions to connect or disconnect loads, informationwill need to be available to the load control. It is preferred that theload control be programmable in order to store such information, howeverthat information may be incorporated at manufacture, or may be learnedby the load control by monitoring and recording parameters e.g. theoperation of various loads, as will be explained further in respect toFIG. 6. As a simple example the current and time parameters of the ovenmay be recorded to compute current vs. time curves from initial turn onuntil reaching temperature for both cooking at different temperaturesand cleaning operation of the oven can be used in subsequent decisionmaking. The higher the oven thermostat is set, the longer it takes forthe thermostat to reach its first cycle and the more frequently itcycles, which information may be utilized to characterize the ovenoperation.

Of course, those time and cycling parameters are also influenced by themass and initial temperature of the food being cooked but about half wayinto the cooking time when the surface temperature of the foodapproaches the oven setting, that influence is greatly decreased. Curvesfor different temperatures as determined by the time from turn on untilfirst thermostat cycle and then the cycle time thereafter can berecorded. When the oven is first started in a new cooking cycle, thetemperature the oven thermostat is set to may be estimated from the timeof turn on to first several thermostat cycles and comparison to thecurves computed for previous operations. While such determinations arenot absolutely accurate they will nevertheless provide an approximation,which load control 25 a may use in determining whether or not to connecta load. In some applications the oven may be configured to communicatedirectly with load control 25 a, to provide useful information such asthermostat setting, cooking time and/or oven temperature.

FIG. 6 shows the preferred embodiment of the invention with variousembodiments of load switches 22 b and 22 c (note load switch 22 a ofFIG. 4 is replaced with load limit 43) and a combination user input anduser feedback module 39. Load limit 43 includes a current control 44 tocontrol current supplied to load 16 which control may, if desired,include complete disconnect of load 16 (an electric oven in thisexample) to/from the power source selected by the transfer switch 15. Asjust one example of a load limit device which may be utilized for 43,consider a remotely controlled light dimmer switch commonly found in thehome and connected to a 250 watt incandescent light bulb. The light bulbwill draw a full load of 250 watts of power if connected directly to the120 volt power but a load limit circuit which in this example is thedimmer will limit the amount of power supplied to the light bulb.

Such load limiting circuits are well known in the art and includecurrent limit circuits which operate to prevent a current from exceedingits prescribed limit, which in the present example is set in response toload control 25 a. Constant current circuits may be also used for 44 andoperate to maintain a preset current through a range of a variable load,which current in this example will be set in response to load control 25a. For clarity, as used in the present specification and claims a loadlimit (or current control) device limits the power supplied to a devicewhich if connected directly to the power source under the sameconditions is capable of consuming more power than that the powerdelivered via the load limit. This usage is in contrast to acontrollable load for which the load itself is controlled so that theamount of power that is consumed when connected directly to the powersource is controlled. As a simple example, remote controlled roomheaters are such a controllable load.

It will be further understood to one of ordinary skill from theteachings herein that other types of control circuits may be utilizedfor 44 to control the power supplied to the load, e.g. phase vectordrive circuits, variable frequency circuits, direct torque control, SCRand thyristor circuits, pulse width modulation and chopper circuits, andvarious soft start circuits, many of which are commonly used as drivecircuits for electric motors. Some of the other circuits which may beutilized operate by reducing the amplitude of the supplied voltage, orby reducing the duty cycle of supplied current or altering the phase ofthe voltage and current applied to the load, and various combinationsthereof. One of ordinary skill will be able to select a particular typeof circuit for use with a particular load type.

Load limit 43 communicates with load control 25 a via communicationlinks 26 a and 36 in order to send and receive data. Interface 29 icouples the communication link 26 a to current control 44 to allow theload control 25 a to operate current control 44. While shown in respectto an electric oven in this example, it will be understood from theteachings herein that load limit 43 may be utilized with other types ofloads, and will be particularly useful with high demand loads, forexample heating and other resistive loads, battery chargers,electrolysis and other electro-chemical loads, in order to limit themaximum amount of power the load draws. One of ordinary skill will alsounderstand that many types of high demand loads do not lend themselvesto operation with particular load control circuits, for example manylarge constant speed rotating machinery loads which are desired tooperate synchronously with relatively fixed voltage AC power and thusare difficult to use with variable voltage control circuits.

Load control 25 a may cause the load to be controlled in discretelevels, for example full, 75%, 50% etc. or may cause the load to becontrolled in essentially continuous fashion, for example 1% or smallerincrements from 0 to 100%. It is desirable however that many loads suchas the oven be continuously provided with some minimum amount of powerto power clocks, timers, control circuits and the like in order thatthey do not have to be reprogrammed after power is completelyinterrupted for a longer period of time. Many ovens and other highdemand loads include switching power supplies to power their clocks,timers, control circuits and the like with these supplies being capableof operating with reduced voltages. Alternatively, the clocks, timersand the like may be provided power via a continuously connected circuit,or may incorporate backup power such as battery operation.

Load monitor 23 b is preferred to be included in load limit circuit 43but may, as well as 35, be omitted if their capabilities are not desiredfor operation of load control 25 a. Load monitor 23 b is similar to 23 aexcept for possible changes to match it to the current controlled anddifferent maximum load. 23 b monitors the electric power supplied toload 16 and communicates via interface 35 and communication channel 36with load control 25 a. This monitor may be utilized to send load power(e.g. current) information to load control 25 a for several purposes.For example, full power oven load characteristics such as initialheating current and current to maintain temperature when heated toprovide current vs. time parameters as previously discussed will allowload control to predict future load. Also, 23 b may be used to enableload control 25 a to determine that the current actually being used hasdropped below the value the current is set to by current controlled 44.This will allow load control 25 a to further adjust current to thusguarantee a lower maximum load without adversely affecting ovenperformance. It is also desirable that communications link 26 a and/or36 operate bidirectionally to provide information to load control 25 athus allowing verification and monitoring of the operation of load limit43.

The oven load information may be used by load control 25 a to detectwhen the oven heating element has just been turned off by the oventhermostat (and thus expected not to turn on again for several secondsor longer). This will allow load control 25 a to use the resulting extragenerator capacity for other purposes, for example to provide additionalstarting current such to as an air conditioner compressor. As a safetyprecaution load control 25 a may also lower the current supply to theoven to a very low value for a short time. This lowering will not impairoven operation while guarding against an unintentional overload ofgenerator 13 in the event the oven thermostat unexpectedly closes due toan unforeseen event such as an opened door. Oven load information may beused to cycle another load out of phase with the oven heating element,that is to only turn on or increase another load such as a batterycharger for a time period after the oven heating element is turned off.Alternatively, the other load can be turned on or increased when theoven heating element is turned off and turned off or decreasedimmediately after the oven heating element is turned on, the momentaryoverlap of the two being handled by the short term higher currentcapability of the generator. These operations will generally be possiblewith any type of load which cycles on and off.

It will be recognized from the teachings herein that the operation ofload limit 43 may be partially or completely incorporated within aparticular load as desired. For example, the current control 44 and/orload monitor 23 b may be incorporated within the oven 16. Alternatively,other loads which are capable of being limited, for example the batterycharger for an electric or hybrid vehicle or the like discussed above,may be connected in a fashion to provide current limit and/or loadmonitoring interconnection to load control 25 a as desired. If the loadhas internal control of its current available, for example such as thebattery charger for an electric or hybrid vehicle or the like, it may beconnected to load control 25 a without an additional current limitcircuit. As with the additional current control 44, load control 25 amay cause the load to be controlled in discrete levels or may cause theload to be controlled in essentially continuous fashion. As with theseparate current control circuit, for loads which have internal clocks,timers or the like which require some small amount of current to operateit is desirable not to completely disconnect them from the power sourcefor long times which will cause these circuits to need to be reset, oralternate continuous circuit power or backup capability can be provided.

Control of individual loads to limit the power supplied to them or powerconsumed by them (one controls the other) under control of load control25 a is desired, particularly during times when the power grid is inheavy use and during times when generator 13 is supplying power. Forexample, heavy current loads like ovens and chargers may still beoperated at reduced current in order to prevent overload of the powersource, as compared to their being entirely disconnected. An oven forexample will take longer from initial turn on to heat to itsthermostatically controlled temperature, but once at that temperaturethe thermostat will be able to control the temperature, assuming areasonable amount of current less than the maximum is still available tothe heating element. In a situation where a power failure occurs afteroven use is started, limiting the current to the oven may allow the ovento be powered from the generator, thus allowing the cooking to becompleted, as compared to an oven which is not so limited and thus cannot be connected to the generator because it will cause an overload.

FIG. 6 also shows load switch 22 b including a switch 34 to connect anddisconnect load 17, an electric clothes dryer, to/from the power sourceselected by the transfer switch 15. Load switch 22 b communicates withload control 25 a via communication links 26 b. Interface 29 j couplesthe communication link 26 a to switch 34 to allow the load control tooperate switch 34. Load 17 may optionally communicate with load control25 a via communications link 40 b. The switch may be operated in anormally closed or a normally open configuration or a latching conditionas known to one of ordinary skill, however it is preferred that loadcontrol 25 a simulate any of those switch types for a given switch. Itis also desirable that communications link 26 b operate bidirectionallyto provide information to load control 25 a thus allowing verificationand monitoring of the operation of load switch 22 b.

FIG. 6 further shows load switch 22 c which includes a switch 34 toconnect and disconnect load 18, an electric air conditioner, to/from thepower source selected by the transfer switch 15. Load switch 22 ccommunicates with load control 25 a via communication links 26 c.Interface 29 k and switch logic circuit 37 couple the communication link26 c to switch 34 to allow the load control 25 a to operate switch 34via logic circuit 37. Logic circuit 37 is preferred to be configurableby communications from load control 25 a to cause it to operate inresponse to power from the transfer switch as a normally open, normallyclosed, latching or special function switch. It is preferred that 37normally be configured by load control 25 a to operate the switch toopen when power to the switch from the transfer switch is lost and tostay open until a command to close is received and thereafter as alatching switch (until power from the transfer switch is lost again). Inthis fashion the load is automatically removed from the transfer switchwhen power is lost, thus eliminating the need to have it disconnected bythe load control. It is further preferred that 37 include a time delayfunction to prevent power from being applied to the air conditioner fora time period after it has been removed in order that the compressorhead pressure can bleed off thus avoiding the possibility of excessivecompressor starting currents. It is also desirable that communicationslink 26 c operate bidirectionally to provide information to load control25 a thus allowing verification and monitoring of the operation of loadswitch 22 c.

FIG. 6 still further shows a combination user input and user feedbackmodule 39 which communicates with load 16 via communications link 38 andcommunicates with load control 25 a via communications link 40. Aspreviously discussed 39 may be incorporated into or supplied byprocessor circuit 33. While shown as a combination input and feedbackmodule, the two operations may be separated into different devices usingcommon or different communications. In the present example, a userdesiring to operate the oven may be alerted that insufficient powercapability exists for such operation, thereby allowing further userinteraction with load control 25 a.

While the load switches 22, load limit 43, controllable loads e.g. 16,17 and 48 are most commonly described herein as being preferred to beseparate from the load control 25, one of ordinary skill will recognizethat the invention may very well be practiced with load controlcircuitry, especially that circuitry corresponding to controlling aparticular switch, limit and/or load, being incorporated within orspecific to a particular switch, limit and/or load, or small numberthereof, which will be referred to herein as load specific controlcircuitry. In this respect the communications which sense overloads andother load related parameters and user inputs e.g. generator monitor 24and environmental, user & miscellaneous devices 21, as well asparticular user interfaces, may be contained within the load or loadcontrolling device, and/or communicate directly with load specificcontrol circuitry.

In particular, in low cost systems, the aforementioned use of powerfrequency may be utilized directly within a load or load control deviceto sense an overload and disconnect the load. One of skill in the artwill recognize that it will be useful to establish priorities for eachsuch device which priorities may be established by incorporatingcircuitry to determine the degree or level of overload, various timedelay operations or combinations thereof in one or more of load switches22, load limit 43, controllable loads e.g. 16, 17 and 48 such that someloads are shed or prevented from connecting more readily than others.For example, the power frequency detector may be set to detect degreesor levels of frequency change, with some loads being disconnected,transferred, limited or prevented from being connected to a particularsource at a small frequency change and others being disconnected,limited or prevented from being connected with larger frequency changesor combinations thereof being utilized with a particular load. Asdescribed herein, particular loads may be switched from one power sourceto another to facilitate a desired optimization or operation of thesystem.

As one example a low priority load may be prevented from being connectedif the power frequency makes more than normal excursions, if evenmomentary, below a given frequency threshold. Such excursions would havea high probability of indicating the generator is close to an overloadand is momentarily overloaded by small and/or short term load increasesfor example such as the starting current of a small motor in a kitchenappliance such as a refrigerator. When a larger or longer term powerfrequency deviation is detected a delay may be incorporated in one ormore of load switches 22, load limit 43, controllable loads e.g. 16, 17and 48, with lower priority loads being disconnected faster than higherpriority loads. In this example a low priority load such as an airconditioner may be quickly disconnected which could very well eliminatethe overload and return the power frequency to normal and thus eliminatethe need to disconnect more loads.

A load circuit may be part of or otherwise incorporated to control oneor a small number of loads, load switches, transfers and/or load limitsin order to sense power frequency to determine the probability ofnearing an overload, being in a small overload, a moderate overload orlarge overload with this information being utilized to control limitingthe current supplied to one or more load, disconnecting or transferringone or more load and/or preventing the connection of one or more load.In addition, other features of the invention described herein may beincorporated, such as preventing the reconnection of a load for a timeperiod after it normally turns off or is disconnected. It will beunderstood that the individual features, e.g. those of 22 b, 22 c, 43and 39 described with respect to the Figures may be rearranged tooperate with a particular load, set of loads or sets of loads as desiredto provide a particular combination of inventive features for aparticular system as will be known to the person of ordinary skill fromthe teachings herein.

With systems where load specific control circuitry is utilized tocontrol the connection of one or a small number of loads in response tothe power frequency, it is desirable to know the loading vs. frequencyof the power source or sources. In particular the characteristics of thefrequency versus load are preferred to be programmed into themicroprocessor either at manufacturer or by the user during installationin order that the microprocessor may know if the load being supplied bythe generator is below, near, slightly overloaded, significantlyoverloaded or highly overloaded. In this respect it is also useful tocontrol the frequency of the A.C. power provided by the power source inresponse to the load on the power source in order that the frequency maybe more accurately utilized by the load specific control circuitry toprevent or remove overloads. This frequency control may be accomplishedby sensing the load on the source and controlling the power frequency byfeedback to the frequency control, e.g. the rotational speed of a gensetor frequency reference of an A.C. inverter.

FIG. 7 shows an example of a mechanical layout of the combination userinput and user feedback module 39, including a display 41 for displayingmessages from load control 25 a to the user and switches 42 a-42 c toallow the user to (among other capabilities) provide commands to theload control 25 a. User commands and messages are conveyed to and fromthe load control 25 a via communications link 40 a, and to and from load16 via communications link 38. Load 16 and load control 25 a may alsocommunicate with each other via 39 (and communications links 38 and 40a). For example, if the user wants to turn on the oven it can instructthe load control to provide power for the oven to be operated in aparticular mode such as full power or at some level of reduced power asdescribed herein. The load control 25 a can offer a set of options tothe user including options to chose the level of operation of thedesired load and corresponding decreases in the level of, or terminationof, operation of other loads. In this fashion the user may communicatewith the load control in order to change priorities to enable the userto obtain power for the desired device. It will be understood that oneor more user input and/or user feedback modules may be provided with anyof the loads in order to allow the user to communicate with the loadcontrol in order to enable the user to operate a desired device, or toallow communications with the load control in order for the user tooperate multiple devices. The feedback and input capabilities may becombined if desired, for example by use of a touch screen as is wellknown in the art.

For example, a user desiring to use the oven to bake for 45 minutes at400 degrees can enter that information to load control 25 a via 39 andkeys 42. The load control will then determine options available to allowoven operation and provide them to the user. The user then selects oneor more (or none) of the options and the load control puts the user'sdesired operation into effect. For example the load control might offerthe user the following options: a) operate the oven at full power byturning off an air conditioner; b) operate the oven at full power byturning off a vehicle battery charger; c) operate the oven at 75% powerby reducing the battery charger current by 50% with an increase of 7minutes to preheat the oven to 400 degrees; d) operate the oven at 65%power by turning off a hot water heater, with an increase of 10 minutesto preheat the oven; e) select option d) and in addition reduce thebattery charger power by 75% and operate the water heater only while theoven heating element is turned off by the oven thermostat. It will beunderstood from the above example that there are numerous capabilitiesand options which may be determined by the load control 25 a andpresented to a user to assist the user to achieve a desired operation.This assistance may be provided in several manners with menu selection,interactive querying and graphical user interface being just a few.

Accordingly, it will be understood that the system of FIG. 4 asimplemented with the various features of FIGS. 6 and 7 will be capableof operation to power ones, which will be understood to include some orall, of a group of loads. The group of loads may include loads which maybe individually switched on and off, loads for which the power suppliedto the load is limited to a known maximum amount, loads which may becontrolled to limit the amount of power they take from the power sourceand loads which are not controlled. It is noted that practice of theinvention will virtually always include loads which are not controlled,which for example will most probably include the generator and transferswitch controller 14 as well as the power supply for the load control25, lighting and electrical outlets for consumer electronic devices. Itwill be understood that the invention may be practiced as needed in aparticular system with only one load comprising any one or moreparticular type of loads and/or without any combination of the abovedescribed types of loads.

FIG. 8, similar to FIG. 4 shows a simplified diagram of anotherembodiment of the invention which includes operation with a third powersource 50 which by way of example is shown as a solar panel andcontrollable load(s) 48. Elements 12, 13, 16, 17, 18, 19, 21, 22 b, 22c, 23 a, 26 a, 26 b, 26 c, 27 a, 27 b, 28 a, 28 b and 28 c are shown,the same as in FIG. 4 except that 21, 27 a and 28 c are changed fromoptional in this embodiment. Load limit 43 is the same as described inrespect to FIG. 6. FIG. 8 further includes load control 25 b similar to25 a of FIG. 4 but having increased capabilities including controllingthe generator and transfer switch instead of 14, as will be describedbelow by way of example. FIG. 8 also includes transfer switch 47,similar to switch 15 except that it is an on-off-on type switch (ascompared to break before make on-on type for prior art switch 15) whichcan connect its output to either power grid 12, or generator 13 orneither, thus leaving only the third power source (solar panel) 50 topower the loads. Transfer switch 47 is controlled by load control 25 bvia communications link 45 (shown at the top of the transfer switch andbottom of the load control) and controllable load(s) 48 communicatingwith load control 25 b via load control communications link 46. One ofordinary skill will understand that in order to simplify the descriptionof the invention FIG. 8 does not show many elements, e.g. circuitbreakers, safety features and the like that are required of an actualsystem and as with transfer switch 15, one of ordinary skill will knowthat transfer switch 47 will be much more complex in practice and isshown herein in simplified form for purposes of explanation.

One of ordinary skill will know from the present teachings, to practicethe invention utilizing the on-off-on type of transfer switch 47. Aswith FIG. 4, the embodiment of FIG. 8 may be utilized to preventoverload of any combination of the power grid service 12, generator 13and third power source 50. It will also be understood that third powersource 50 may be operated while the power grid is connected in order toreduce the power supplied by the power grid, or even to sell power backto the power utility, however it will be recognized that in suchparalleled systems when the power grid fails it is important todisconnect the power grid from the generator in order to prevent damageto the generator or possible harm to workers who are repairing the gridfailure. Additionally, when the generator is connected by transferswitch 47 to power the loads it is likewise important not to transfersubstantial (i.e. damaging) amounts of power from the third power sourceto the generator to prevent damage to the generator. Because of this itis important to monitor the generator current output or otherwise toconnect an additional load or disconnect the generator when the thirdpower source 50 can provide enough current to power the loads.

Communications link 27 a is utilized for communications betweengenerator 13 and load control 25 b via power source monitor 49 in orderthat load control 25 b may start and stop the generator in response topower grid failure (sensing link to power grid is not shown) or asotherwise needed. Note that communications link 27 a may connectdirectly from generator 13 to load control 25 b as previously described.One of ordinary skill will understand from the present teachings thatthe third power source, solar panel 50 is representative of one or moreadditional individual power sources which may be utilized with theinvention. A solar panel which is made up of individual photovoltaiccells that convert sunlight to electricity is chosen in FIG. 8 by way ofexample with the teachings of the inventive concepts being applicable toindividual and combinations of other types and numbers of power sources,e.g. stored energy, wind, water and geothermal types of power sources inaddition to solar. As with communications link 27 a, the solar panelcommunications link 27 c may be connected directly to load control 25 bif desired. When solar panel 50 and generator 13 are connected directlyto load control 25 b power source monitor 49, load monitors 23 a and 23c and their associated communications links may become redundant and maybe eliminated with respect to monitoring the generator and solar panelrespectively.

Solar panel 50 has a power output via connection 51 which is connectedwith the output of transfer switch 47 to provide power to the loads asis well known in the art, e.g. it is synchronized to and paralleled withthe power from transfer switch 47. The power output from the solar panelis measured via load monitor 23 c and communicated to power sourcemonitor 49 via communications link 27 d. Load monitor 23 c is similar to23 a except for possible changes to match it to the maximum output powerof the solar panel. Power source monitor 49 functions in a mannersimilar to generator monitor 24, receiving generator and power grid loadinformation from 23 a via communications link 27 b and optionallycommunicating via communications link 27 a. As explained with respect toFIG. 4, load monitor 23 a may also monitor power supplied by the grid.

Additionally, power source monitor 49 receives solar panel power outputinformation via 23 c and communications link 27 d and optionallycommunicates with solar panel 50 via communications link 27 c. The powersource monitor 49 communicates with load control 25 b via communicationlink 28 a and optionally 28 b as previously described in respect toFIGS. 4 and 5 but additionally includes information and communicationswith respect to solar panel 50. As will be known to one of ordinaryskill from the teachings herein, the power source monitor and loadcontrol may be expanded or duplicated to handle more power sources thanthe generator 13 and solar panel 50. Connection of those extra powersources to the system may be via extra transfer switch circuits as withgenerator 13, or via paralleling as with solar panel 50, and will beaccommodated by load control 25 b for control of the loads beingpowered. As previously explained with respect to generator 13, if thepower source(s) provide information about their operating parametersfrom their own control and/or monitoring systems that information may becommunicated directly to load control 25 b and power source monitor 49along with its sensors and communications link may be eliminated withrespect to those power sources.

The operation of the embodiment of FIG. 8 is similar to that of FIG. 4,however additional capabilities of powering loads 16-19 and 48 from thesolar panel 50 are provided as well as interacting with and controllingload(s) 48 directly by load control 25 b to set its maximum loadpresented to the power source(s). For example, a controllable load 48may be a Lasko Model 5350 room heater which can be remotely switchedfrom off to 900 watts to 1500 watts via wireless communications link viaload control 25 b. Solar panel 50 is connected to the output of thetransfer switch 47 to provide additional power to the loads whenenvironmental conditions permit, thereby reducing the amount of powerrequired from the other power source(s). In particular, during periodsof low load demand when power is available from 50 the load control 25 bis preferred to communicate via 45 to cause transfer switch 47 to switchto its off position in order to power those of the loads 16-19 and 48which are consuming power to receive that power from 50.

Controllable load(s) 48, such as the aforementioned room heater may bepowered by solar panel 50 and controlled to either heat at 1500 watts ifthere is enough power available and heating is desired because of a coldroom or outdoor temperature (sensed by sensors 21), or may be reduced to900 watts if a higher priority load needs power or the solar panel 50 isincapable of providing power for the high setting, or may be switchedoff if the room temperature is high enough or solar panel 50 can notprovide 900 watts. It will be recognized in this example that when theroom temperature reaches the thermostat temperature of the heater 48(which may be set by load control 25 b or directly on the heater by auser), the heater will turn off its heating element thereby drawingminimal power. Load control 25 b may nevertheless turn off the heater toavoid a sudden overload of the solar panel 50 should the roomtemperature cool to the point where the heater's thermostat turns theheating element on again.

Accordingly to the present example, low cost power is selected by loadcontrol 25 b to power the loads while at the same time the load controlwill communicate to various components of the system to monitor (e.g.via load monitor 23 c) and control power supplied to several loads eachof differing types including high priority loads such as lights 19,switchable loads such as by load switch 22 b to clothes dryer 17,limitable loads such as via load limit 43 to oven 16 and controllableloads such as the heater 48 to allow loads of various priorities to bepowered by the low cost power source while at the same time preventingoverload of that source. Load control 25 b will monitor and controlpower demands by the various loads so as to not exceed the availablepower from a given power source or set of power sources. If demandincreased beyond what a power source such as the solar panel 50 iscapable of providing, the load control will decide to either not connectthe additional load(s), or to connect but control power supplied to theadditional load(s), or to connect additional power source(s) such asgrid power 12, or start and connect the generator 13, or other powersources (not shown) thus providing additional power for the additionalloads. The decision making by load control 25 b is preferred to be basedon one or more of user input, load priorities, load parameters, powersource parameters, power cost and environmental parameters in order toprevent overload of the power source(s) powering the loads.

In particular, the decision to connect to additional power sources ispreferred to be made according to the priority of the load(s) to beconnected, availability and cost of the power from the various powersources which are available to provide additional power, or according toother decision making criteria which is provided to the load controlduring manufacture, installation or afterward by an operator, either bythe operator's changing and storing priorities or by the operator'sinstant override of stored priorities. It will be understood that morethan the three power sources may be accommodated. There may be one ormore wind turbines, solar panels, fuel cell, generators and the likeprovided in the system in addition to the grid power as one of ordinaryskill will find desirable to fit a particular application. In systemsrequiring high reliability there may also be multiple connections to thepower grid, the multiple connections being provided by different gridservice paths, or even to multiple power grids provided by differentutilities. Such multiple connections are known in the art to be used inbroadcasting and medical facilities. Of course, as previously describedthere may also be many loads of different types to be controlled by loadcontrol 25 b using the devices, capabilities and features describedherein.

A controllable load 48 may be of any type where control of the powerconsumed by the load is provided within the load, e.g. those describedin respect to FIG. 6 or those which include any of the various circuitsdescribed with respect to current control 44 of FIG. 6, and those whichare otherwise controllable without requiring a separate load limit 43 orload switch 22 b or 22 c as previously discussed. A three way light bulbis such a controllable load. Other such controllable loads include theabove mentioned low and high power oven and clothes dryer and the TeslaMotors vehicle High Power Connector and battery charger. Controllableload 48 communicates with load control 25 b via communications link 46to provide load control communications, which may be single direction orbidirectional as desired.

FIG. 9 shows a diagram of load control 25 b, similar to FIG. 5 with thesame elements 26 a-26N, 28 a, 28 b, 29 a-29 h, 30, 31 and 32. Inaddition, load control 25 b has additional interface circuits 29 i and29 j and communications links 45 and 46 to provide communications withtransfer switch 47 and controllable load(s) 48 respectively. One ofordinary skill will understand that processor circuit 33 b of 25 b ispreferred to have additional capabilities as compared to processorcircuit 33 a of FIG. 5 in order to accommodate the additionalcapabilities such as may be needed in relation to solar panel 50,transfer switch 47 and controllable load(s) 48. Implementation of suchadditional capabilities will be within the ability of one of ordinaryskill from the teachings herein.

It is preferred that the operation of the embodiment of FIGS. 8 and 9 besuch that power is provided to each individual load at times and inamounts, and from one or more of a plurality of available sources as aredesirable to minimize cost and maximize reliability for a given set ofcircumstances, as controlled by load control 25 b. It is furtherpreferred that the operation of load control 25 b be performed at leastin part by taking into account established priorities for one or moreindividual loads, established parameters for one or more loads,established parameters for one or more power sources and monitoringparameters for one or more power sources and one or more loads. It isfurther preferred that the operation of load control 25 b be performedto allow input from one or more user in order to allow changing ofpriorities of loads and changing of the operation of one or more load soas to change at least that load's current in operation.

FIG. 10 shows a simplified diagram of the embodiment of FIG. 8 whichincludes additional capabilities for management of loads presented to apower source wherein the power source provides power in one or moreform, and the loads consume power in more than one form, e.g. electricand heat. FIG. 10 includes elements 12, 13, 16, 17, 18, 19, 22 b, 22 c,25 b, 26 a, 26 b, 26 c, 27 a, 43, 45, and 47 as in FIG. 8. Otherelements of FIG. 8 are omitted from FIG. 10 for simplicity. Additionalelements are included in FIG. 10 for the purpose of recovering power inthe form of heat from generator 13 as controlled by load control 25 b.The elements of FIG. 8 which are not shown in FIG. 10 will be known tobe available for inclusion in FIG. 10 as desired. Generator 13 isassumed for the teachings herein given by way of example and inparticular with respect to the instant explanation of heat transfer withrespect to FIG. 10, as being of a type such as a fuel cell, internalcombustion engine, battery or battery array, or the like havingsignificant heat generation as a byproduct of its operation. Generator13 will further be assumed to have a liquid or gaseous coolant systemwhich may utilize glycol, water, steam or any other coolant suitable foruse with generator 13, along with a radiator or other heat exchanger forremoving such heat thereby cooling the generator. As used herein thecoolant will be referred to as a fluid, even though it may be in agaseous or mixed state form. In the system of FIG. 10, the coolant issupplied from the generator's cooling system via piping (piping shown byheavier lines) 58 to electrically controlled valves 54 and 55 to heatexchangers 52 and 53 where the coolant loses heat to the fluid on theother side of the heat exchangers. The cooler fluid (which may changephase from gaseous to liquid due to cooling in the heat exchanger), isthen returned to the generator via piping 59 (and change phase fromliquid to gaseous in the generator). Circulation of the coolant may beprovided by the cooling pump in generator 13, or externally by anadditional pump or pumps (not shown). In this manner the excess heatfrom 13 will be removed and utilized to heat other needed devices and/orsystems. As noted FIG. 10 is a simplified diagram and one of skill willknow there are several operation details and considerations which willbe pertinent to the proper operation of the generator, load control andheat exchangers in a particular system. For example, it is desirablethat additional flow control, mixing and safety valves, temperature andpressure sensors and/or pumps are included in the systems. These are notshown but nevertheless necessary as will be known the one of ordinaryskill.

Heat exchanger 52 operates to transfer heat in the coolant from 13 toheat cold water 61 from a supply such as a well or municipal waterutility to be used as domestic hot water 60. Heat exchanger 52 ispreferred to be a double wall construction type to prevent leakage ofcoolant into domestic hot water. The domestic hot water may be heated toproper temperature, usually around 125° F. directly by heat exchanger 52or may be only partially heated to its desired temperature with heatingto the desired temperature accomplished by another heating stage (notshown) as is well known in the hot water heating industry. Similarly,heat exchanger 53 operates to heat returning glycol or other fluid 63used in a radiant heating system to the proper temperature, usuallyaround 150° F. to provide a supply of radiant heat fluid 62 or onlypartially with heat to the desired temperature accomplished by anotherheating stage (not shown) as is well known in the hydronic heatingindustry. Temperature sensors (e.g. RTD and other resistive sensors,thermocouple, silicon junction, silicon bandgap, thermostats oraquastats) inside the heat exchangers 52 and 53 sense the temperature ofthe domestic hot water supply and radiant heat supply respectively andconvey those temperatures to load control 25 b via domestic heat senselink 64 and radiant heat sense link 65 respectively as known in therespective industries. Load control 25 b operates to adjust the openingof one or both of valves 54 and 55 to maintain radiant heat supplyand/or domestic hot water supply at or near a desired and preferablyconstant temperature. Valve opening may be controlled such that thevalve is either fully open or closed with heating controlled by the timeof opening, or partially opened with heating controlled by the amount ofopening, or a combination of the two. [Para 161] FIG. 10 elements 52-65will be understood to be common and ordinary components of hydronic andhot water heating systems as are known to the person of ordinary skill.In some systems it may be desired that temperature sensors be omitted(but not relief valves) where the heat exchanger 52 or 53 can onlypartially heat to desired temperature and another heating stage is used.It is desired that both the domestic hot water system and radiant heatsystem include additional heating stages to ensure both systems operatewhen generator 13 is not running. When generator 13 is running and atoperating temperature, if the domestic hot water temperature and/orradiant heat temperature as sensed via 64 and 65 respectively is belowthe desired temperature load control 25 b causes opening of thecorresponding valve. Generator temperature will be made available to theload control via communications link 27 a. It is desired that theradiant heat system be controlled so that when generator 13 is notrunning the radiant heat fluid is not circulated through heat exchanger53 which might lead to some inefficiencies due to heat loss in 53. Otherarrangements of the system and its components will be possible from theteachings herein.

As another example, one or more battery pack(s) in an energy storagesystem such as that utilized in an electric or hybrid vehicle, or windturbine, and in particular a battery pack stored in an unheatedlocation, may be heated by connection to radiant supply 62 or by aseparate heat exchanger in order to prevent excessive cooling and/or tomaintain the temperature of the batteries at or near optimum temperaturefor the type and intended use of the battery. In addition, duringcharging the excess heat from the battery may be removed by the samesystem and used to heat other devices or systems, for example such asthe radiant heat supply or domestic hot water. The integration andoperation of such additional heating and cooling connections and controlthereof by the load control 25 b will be within the skill of one ofordinary skill from the teachings herein.

Also, it will be desirable to regulate the cooling of the generator 13,which is provided by its own radiator, in order that sufficient heat isavailable to the heat exchangers when needed, and when heat is notneeded by the heat exchangers the generator radiator dissipatessufficient heat to keep the generator properly cooled. This heatmanagement may be had by proper choice of the generator's coolingthermostat temperature, somewhat above the highest output temperature ofthe heat exchangers. In the above example if the generator's thermostatis chosen to be 160° F. it will open and cool the generator independentof the heat exchangers if sufficient heat is not drawn away from thegenerator by the heat exchangers. The proper handling of these operationdetails and considerations will be apparent to one of ordinary skillfrom the present teachings.

It may be desirable that the system of FIG. 10 be used with a fuel cellwhich has its electrical output connected to the output of the transferswitch in the same fashion as the solar panel 50 of FIG. 8. This willprovide more continuous heat for use by the heat exchangers 52 and 53.Alternatively, because most fuel cells include one or more internal heatexchanger that heat exchanger may be used to heat the domestic hot waterand/or the radiant heat. As with the generator example above provisionsmust be made to ensure proper cooling of the fuel cell in the eventsufficient heat is not drawn away by the heat exchanger. The properhandling of operation details and considerations will be apparent to oneof ordinary skill from the present teachings.

The coupling of a second form of energy (heat) from generators and otherpower sources such as fuel cells for use in the heating of domestic hotwater and radiant heat supply is given by way of example and one ofordinary skill will recognize from the present teachings that otherforms of energy may be produced, recovered, transmitted, stored and/orutilized to power devices or systems for which it is desirable toutilize that energy. Such systems may utilize the teachings and featuresof the preferred embodiment of the present invention to benefit fromimproved management of energy therein as will be known to one ofordinary skill. For example, some vehicles are known to utilize storedcompressed air for power and energy may be managed in a gaseous formutilizing the inventive concepts disclosed herein.

FIG. 11 shows a simplified diagram of a load which may also be utilizedas a power source which the present invention may be used with. In thisexample the load is shown as a battery (or battery array) which may becharged to store power. Such batteries may be part of a green powersystem such as a solar panel, wind or water turbine and may bepermanently located or otherwise such as installed in an electric orhybrid vehicle, described in more detail with respect to FIG. 12. Otherforms of energy storage may be utilized in place of the battery, as longas suitable interface devices to store and recover stored energy areused as will be known to one of ordinary skill from the teachingsherein. For example, energy storage forms using compressed air in acontainer, heat in a vessel, fluid pumped to an elevated reservoir,mechanical such as a flywheel or spring, and many other suitable formsmay be resorted to by the person of ordinary skill.

In FIG. 11 a connection 71 a from the transfer switch (preferred to bemade via a circuit breaker which is not shown), for example a highcurrent 240 volt connection such as discussed herein with respect to avehicle battery charger, is made to the input of battery charger 66 andoutput of DC to AC inverter 67. The output of the battery charger 66 isconnected to the battery 68 and the battery 68 is also connected to theinput of DC to AC inverter 67 which when it operates is preferred tosynchronize with and parallels power (if any) available at the transferswitch output. U.S. Pat. No. 7,338,364 describes this type of powerinverter. It is possible that both charger 66 and inverter 67 will be inclose proximity to the battery 68 in order to minimize wiring costs andit is possible that both charger 66 and inverter 67 will be combinedinto one instrument. Both charger 66 and inverter 67 are connected toload control 25 (not shown) via communications links 69 and 70. Thecommunications may be combined in one communications link if desired. Inthis fashion power from the transfer switch may be utilized to chargethe battery or the battery may be used to power the inverter 67 toprovide AC power to the other loads or to the power grid, all undercontrol of load control 25. In particular the battery array of anelectric or hybrid vehicle may be utilized in order to provide backuppower to one or more loads in the event of a failure of the power grid.

Recalling that many homes only have a 100 amp service from the grid itnormally would be unwise to use a 90 amp connection from the transferswitch to the battery charger due to the risk of overloading the serviceconnection. When, as in this example, the charger can be controlled bythe load control to keep its maximum load to the service at a much lowerlevel, for example 20 amps, or to otherwise prevent overload of theservice connection, a larger capacity connection may be utilized as willbe understood from these teachings. The load control may at any timemonitor the charge of the battery 68 via the charger 66 andcommunications link 69. If the battery has a sufficient charge and theload control needs to have additional power available, such as during agrid outage or during a high load conditions, the load control may turnoff the battery charger 66 and turn on the DC to AC inverter 67, therebytaking power from the battery to be used elsewhere.

In this example, having the 90 amp connection to the battery inverter 67will allow a significant amount of power to be supplied, almost enoughto replace the entire 100 amp service in the event of a grid powerfailure. Of course, the power taken from the battery may be utilized forother applications as previously discussed, including supplementing gridpower during heavy loads or expensive power rates or even selling powerback to the utility. One will recognize that it is also possible tocharge the battery with cheap power from another source such as solarpanel 50 or at a time of availability of cheap power from the grid 12such as at night. That cheap power which is stored in the battery maythen be used when power from the grid (or other sources) is moreexpensive, or may even be sold at a profit. Control of charging anddischarging of the battery 68 by load control 25 may also take intoaccount the timing and need of power for other uses as well, such asdriving the vehicle which the battery is installed in.

FIG. 12 shows a diagram of an embodiment of the invention which is usedwith an energy storage battery 68, optional communications link 73 andcharging generator 72. Battery 68 and DC to AC inverter 67 areconfigured as a backup power supply to be used in the event of a powergrid failure. Power grid 12, loads 16-19 and 48, load control 25 b, loadswitches 22 b and 22 c, load limit 43, communications links 26 a-26 c,45 and 46 and transfer switch 47 are described above as in FIG. 8.Battery 66, DC-AC inverter 67, battery 68, communications links 69 and70 operate as described above in respect to FIG. 11, except that thebattery charger 66 is connected to the output of the transfer switch via71 c whereas the output of DC to AC inverter 67 is connected to an inputof the transfer switch 47 instead of to the output of the transferswitch as in FIG. 11. If it is desired to provide power from 67 to thepower grid, synchronization with and parallel operation may be obtainedwith the connection moved to the output of the transfer switch. It willbe recognized that it will be necessary to disconnect the power grid inthe event it fails.

The embodiment of FIG. 12 will find use as a home backup system and inparticular where the battery (or battery array) 68 is contained withinan electric vehicle which is charged by battery charger 66 or a hybridvehicle which may be charged by battery charger 66 or by a generator 72.It will be known that generator 72 may be of any type suitable for usewith the battery 68, or with a vehicle which contains the battery, forexample an internal combustion engine or more preferably a fuel cell. Itwill be understood that when the battery 68 is part of a vehicle thatbattery charger 66 detect and convey to load control 25 b when it isconnected to the battery and similarly DC to AC inverter 67 communicateto load control 25 b when it is connected to the battery. Of course,when the two are configured to be connected simultaneously, e.g. by asingle connector, either charger 66 or inverter 67 may convey thecommunications via a single connection. When the vehicle includes an onboard generator operable to charge the battery, load control 25 b maycommunicate with generator 72 as desired via 73, it being preferred that73 be wireless, or included in the communications link 69 or 70. DC toAC Inverter 67 may also be located in the vehicle. When the vehicleincludes an operating system to manage those of 66, 67, 68 and/or 72which are located in the vehicle, communications between those elementand load control 25 b may be handled via a communications link with thatoperating system.

Battery charger 66 will be turned off by load control 25 b wheneverinverter 67 is selected by transfer switch 47. Generator 72 is preferredto be utilized to charge battery 68 whenever the battery is being usedas an energy source for backup power and the battery becomes dischargedfrom that operation or is already in a discharged state when needed forbackup power. It is preferred that load control 25 b operate todetermine the level of charge of battery 68 at or below which it isdesirable to start the generator 72 to charge the battery in order tomaintain or extend the amount of energy which is available to power DCto AC inverter 67 to be utilized as backup power in the event of failureof the power grid 12. It is additionally preferred that in normaloperation battery charger 66, under control of load control 25 b,operate to charge battery 68 with low cost power, for example duringnight hours or from a low cost power source such as solar, wind or waterpower as previously discussed. Thus battery 68 may be kept at or near afully charged state using low cost energy and used to power inverter 67during power outages. Although the battery 68 and related elements ofFIGS. 11 and 12 are not shown in FIGS. 4-10 the teachings relatedthereto generally may be incorporated with respect to any of FIGS. 4-10.FIG. 11 does not show a battery charger other than 66, however it willbe understood that the teachings of FIG. 12 and in particular withrespect to generator 72 will also be applicable to the system of FIG.11.

If battery 68 is discharged to a predetermined level due to extended usefor backup power or lack of initial charge, generator 72 may be startedby load control 25 b (or otherwise by the vehicle's own operatingsystem) to recharge the battery. Load control 25 b is preferred tomanage loads in order to minimize the discharge of battery 68 whilemaintaining a user preferred level of power to various loads, eitherduring normal backup operation or during charging by generator 72 orboth. As an additional consideration, while generator 72 is preferred tobe a fuel cell with no dangerous or annoying emissions, if generator 72is an internal combustion engine or similar generating device whichemits dangerous or annoying emissions it is preferred that the facilitysuch as a garage in which it is housed (if any) include provisions forsuitable ventilation and other protection against such emissions. Suchprotection is desired to be controlled by or otherwise monitored by loadcontrol 25 b in order to ensure safe operation of generator 72. In anexample of such protection, a garage will be fitted with an exhaust fanand monitor for potentially dangerous emissions (e.g. a carbon monoxidemonitor) which fan is started when or near the time which the generatoris started with the fan not being shut off by load control 25 b untilafter generator 72 is stopped and carbon monoxide levels (and any otherpotentially dangerous emissions) are verified via the monitor(s) to beat or below safe levels. The exhaust fan is preferred to be otherwisecontrolled by load control 25 b to run whenever the level of anyemission is above safe levels.

FIG. 13 shows a simplified diagram of a combination of load coupler 80configured with a load 18 shown as a typical air conditioner andcommunicating with load control via link 26 c in order to control thecoupling of power from the transfer switch to the load as taught aboveand as will be explained further in respect to FIGS. 14 and 15. Controllink 26 c may be of any type previously described but will be shown byway of example in FIGS. 14 and 15 below as a wireless link. As describedherein the power and loads may take on various forms however forpurposes of explaining the invention description will be given by way ofsingle or multiple phase electrical power in commercial voltage andcurrents available to homes powering loads which are relatively heavy ascompared to the utility service, for example electric air conditioners.Accordingly, 80 may also be configured as a load limit 43 if desired toprovide control of suitable loads as discussed herein.

FIG. 14 shows a detailed diagram of a commercially valuable embodimentof load coupler 80. Power from the transfer switch is controllablycoupled to the load 18, shown in this example via controllable relay 34which may be a latching or a simple type as desired. If desired, relay34 may be replaced by or combined with a current control circuit 44which communicates unidirectionally or bidirectionally withmicroprocessor 37 to control or limit current to the load as animplementation of load limit 43 previously discussed. It is preferredthat by using microprocessor 37 and user interface 77, load coupler 80may be manufactured as a standard device with each of multiple devicesconfigured via the user interface 77 at the time of installation in aparticular system to match the particular load being controlled.

Additionally, the load coupler 80 may be designed such that optionalfeatures, for example such as the aforementioned current control, ordifferent size latching or simple relays, may be installed aftermanufacture as desired. For example, it will be desirable for theinstaller to have the ability to install a current control and/or relayof proper current rating to match the load. Once a unique name or otheridentifier is assigned to a particular coupler 80 via the user interface(or in manufacture), other configuration and test settings may be madevia the user interface 77 or via a load control 25 or both. It isfurther desired that the installer have the capability to operatecurrent control 44 and/or relay 34 and to operate, calibrate, testand/or check other functions such as battery charge, communicationsintegrity and operation of sensing functions from either the userinterface 77 or the load control 25 or both.

A latching relay which operates independent of external control from 37to drop out and latch open when the voltage from the transfer switchrises above drops below known levels (setting a range of permissiblevoltage) is useful in protecting the load. This type of operationachieves high immunity from momentary disconnection due to over andunder voltage conditions which frequently accompany power losssituations. Utilizing a relay which automatically drops out and latchesprovides a degree of protection which is independent of the othercontrol circuitry, e.g. the relay will drop out independent of thecontrol circuitry but the aforementioned capabilities may also beprovided via microprocessor circuit 37 if desired.

If utilized, the latching operation may be configured to latch openonly, or latch open and closed. Additional protection including noiseand spike filters, snubbers, limiters or absorbers such as transientvoltage suppressors (e.g. TVS diodes) may be utilized (not shown) toprotect the load from such unwanted occurrences as will be known to theperson of ordinary skill in the art from the teachings herein. Forexample, when a simple relay is used momentary high voltage spikes maybe passed to the load causing unwanted operation or damage and momentarydisconnection of the load due to brown out or other low voltageconditions may cause unwanted operation or damage. For example, a shortdisconnection during a brownout may cause an attempt to restart an airconditioner compressor with a high head pressure as previouslydiscussed. By use of a latching relay operating to drop out and latchindependent of control circuitry an extra degree of load protection isprovided.

Because microprocessors are low voltage and low current devices acurrent driver and/or voltage translator must often be used to provide ahigher voltage and/or current to energize the coil of relay 34 than themicroprocessor alone can provide. Such current driver (or voltagetranslator) may be incorporated in the microprocessor circuit 37, or therelay 34 or elsewhere. Accordingly, the energizing the coil of relay 34may be dependent on power from the transfer switch (which would directlyor indirectly power the relay coil) thus allowing short voltagetransients to cause the current to the relay 34 coil to lower to thepoint of allowing the relay to briefly disconnect the load. That briefdisconnection can happen even though microprocessor circuit 37 maintainsa constant command to the relay coil driver circuit intending to keepthe load energized. In this example the use of a latching relay whichwill latch off in the event of a momentary dropout will avoid arelatively quick restart of the load and the resulting damage. Othertypes of relays and disconnect and connect operations may be utilized toprevent or reduce such problems if desired as will be known to theperson of ordinary skill in the art from the teachings herein.

If a latching type relay or other circuit more complex than a standardrelay is used, it is preferred that relay position circuit 79 beincluded in order that the microprocessor may know which position therelay or other circuit is in and in particular may know when the relaydrops out. Such knowledge will be useful for example when voltagetransients not timely sensed (or not sensed at all) by themicroprocessor 37 occur. The relay position information will also beuseful in the event the microprocessor is not programmed to store therelay setting when a change is made, or when the microprocessor iscaused to reboot such as might happen in response to a monitoringroutine, or as a failsafe to verify that the relay actually switches tothe position commanded by the microprocessor.

The control of the relay is provided by the microprocessor 37 inresponse to various inputs and programming as described elsewhereherein. In particular a current monitor 23 d provides a measure ofcurrent provided to the load to 37 and a voltage monitor 78 provides ameasure of the transfer switch voltage to 37. While the control of thecoupling of power from the transfer switch to the load is shown in FIG.14 by way of example as a relay, it may also be performed by othercircuits as well, for example by way of current control, currentlimiting or otherwise as will be known to the person of ordinary skillfrom the teachings herein.

A battery & battery charger 74 provides backup power to the variouselements of 80 as desired in order that they may continue to operate inthe absence of power provided by the transfer switch. The output of 74may be AC and/or DC at any voltage desired to fit a particular use andapplication of 80 as will be known to the person of ordinary skill inthe art from the teachings herein. In the preferred embodiment of FIG.14 it is desired that the battery be a rechargeable type and that it becharged whenever AC power is available from the transfer switch. It isfurther preferred that 74 include a switching type power supply toprovide the desired DC and/or AC power at various voltages (andfrequencies) which are needed by the various circuits within 80 in orderthat all desired circuits are operational whether AC power is availablefrom the transfer switch or not. In this manner 80 may operate toprovide control of the coupling of power to the load as taught herein.In particular, in the event grid power is lost and there is a delaybefore power is restored via the transfer switch, microprocessor 37 willhave recorded the state of power consumption by the load immediatelybefore power loss, will have a timer to determine the amount of timepower has been lost and will have available load characteristics and/orother data which is used to determine the manner in which backup powermay be coupled to the load when available. As one example, when an airconditioner compressor was running when the power is lost themicroprocessor will know not to couple backup power from the transferswitch to the air conditioner until sufficient time has passed to allowhead pressure to bleed off thus preventing excessive starting current orcompressor stall. The user interface 77 may operate to provide variousinteraction between the user and microprocessor, and via themicroprocessor to the load control as described elsewhere herein and inaddition allows an installer to configure 80 to operate with aparticular load.

In particular, it is desired that the microprocessor and/or load controlmay be accessed via user interface 77 in order to identify theparticular load (and its characteristics) to the system and configurethe system and/or microprocessor 37 to the particular load at the timeload control 80 is installed in the system, or at subsequent times forexample such as when the load or its characteristics are changed. Thisuser capability will facilitate physical installation of 80 in nearproximity to the load, for example at an outside air conditionercompressor and will reduce the number to trips between the load (and 80)and the load control which likely will be located near the transferswitch, the utility service entrance or a location convenient to thehome owner.

FIG. 15 shows a commercially valuable embodiment of load control 80 likethat of FIG. 14 but which is physically separated into two sections, ahigh voltage section 80H and a low voltage section 80L. The two sectionswill facilitate design and manufacture to meet a particular application,including various testing and regulatory approvals. The low voltagesection may be configured to provide a desired level of features andfunctionality for a particular system of level of systems and the highvoltage section may be configured to provide a desired level of featuresand/or type of control of the load. Both sections may for example haveoptions which may be installed after manufacture, such as theaforementioned capability of having relay and/or current control optionsinstalled at the time of installation to match operation of 80 with aparticular load. It is desired that the interface between the low andhigh voltage sections be compatible for all combinations thereof. Forexample, the low voltage section may be configured in several modelsstarting with a basic, low cost model with wired communications and asimple user interface to allow the user to only assign an identifier toeach device in a small system with advanced, higher cost models (orinstallation of options) providing more features such as keypads, LCDdisplays, additional configuration and advanced programmabilitycapabilities, wireless communications, etc.

The high voltage section may likewise configured in several models fromlow cost basic to higher cost advanced models (or installation ofoptions) to accommodate various power sources and loads such asparticular operating voltages, maximum load currents and multiple powerphases. In this fashion a manufacturer may sell a small number of lowvoltage section models and a small number of high voltage section modelswith a particular system installer choosing the type and number of eachmodel and options to match the particular system being installed.Additionally, separate high voltage models may be utilized for relay orcurrent control or a single model may incorporate both relay and currentcontrol or may incorporate multiple relays and/or current controldevices. The high voltage devices may be controlled by a lesser numberof low voltage sections or even a single low voltage section if desired,the latter being particularly well suited for utilizing the inventionwith, or incorporating the invention into, the transfer switch, powerentrance service panel, a power sub-panel or any of the various localpower generating devices taught herein, for example with respect to FIG.8.

As an example of the usefulness of separate sections and options, amanufacturer might offer only one low voltage section with options for:user keypad, LCD display, relay 83 and wireless communications link 29 kand two high voltage sections, one for single phase and one for multiplephase power, each with options for: current sensing, latching or simplerelays of differing voltage and current ratings, current controlcircuits for differing voltage and current ratings.

The physically separated sections 80H and 80L will also facilitateinstallation and operation of the invention. For example, by keeping allof the high voltage components in the 80H section safety is enhanced byonly having a minimum number of circuits which are potentially exposedto high voltages and to electrical interference and noise created bycontrolling high voltages and currents. Additionally, physical size iskept to a minimum thereby facilitating installation of that section nearto or within the enclosure which houses the load. On the other hand, thelow voltage section may be designed without overdue attention to highvoltage, high current, interference, noise, regulatory and safetyconsiderations. For example, by utilizing only low voltages in the 24volt and below range various regulatory approvals will not be needed forthe 80L section.

FIG. 15 shows an embodiment of the invention where high voltage and highcurrent (e.g. a 240 VAC 50 amp supply) from the transfer switch iscoupled to the load 18 via a relay with a 24 VAC control (coil). Inaddition, a class 2 (dry environment) or class 3 (wet environment) 240volt to 24 volt transformer 81 is utilized to provide low voltage forthe 80L section. It is desired that 81 be connected to the 240 voltpower physically close to 80H in order that the 24 volt output may beused by microprocessor 37 (via 78) to monitor the 240 volt power fromthe transfer switch. For example, in a simple form the 24 volt AC outputof 81 is monitored by the microprocessor circuit 37 to determine andcompare the RMS voltage to a high and a low limit. If desired, theamount of time that voltage exceeds the high limit or falls below thelow limit may be monitored as well. If the voltage falls outside ofeither acceptable limit for more than a predetermined time then themicroprocessor circuit 37 may actuate relay 83, which in turn causesrelay 34 to open thus disconnecting the load 18 from the transferswitch. The parameters for the high and low voltage limits as well asthe aforementioned time duration are preferred to be programmable inorder to protect load 18 from damage as well as to prevent it fromcontributing to overload and possible damage of the backup power sourceduring a power outage as will be known to one of ordinary skill in theart from the teachings herein. If desired a current monitor 23 d, suchas the aforementioned current transformer may be incorporated, as wellas a relay position circuit 79 may be included to facilitatemicroprocessor circuit 37 control of power coupling to load 18.

Supply 81 is preferred to be a 24 volt AC transformer to provide lowvoltage power to section 80L and is chosen because it is a readilyavailable standard device used in home heating and air conditioningcontrols, doorbells and elsewhere. Other AC or DC supplies may beutilized if desired, for example plug in 120 volt to low voltage AC orDC power supplies frequently referred to as “wall warts” may beutilized. In addition, the battery charger and/or battery of 74 may beincorporated as well. It will be noted that if a power supply whichincorporates a voltage regulation circuit is utilized, the regulationwill prevent monitoring of the voltage of the power from the transferswitch except for the loss of power causing the output of 81 to shutdown. If a simple voltage presence is all that is desired then that maybe monitored via microprocessor circuit 37 but if a more accurateindication of the actual voltage is needed other provisions will berequired as discussed elsewhere herein.

Relay position circuit 79 is simply shown in the drawings as aconnection from the relay 34 to the microprocessor circuit 37. The relayposition circuit is preferred to incorporate a switch or switches whichare coupled to the position of the movable portion of the relay, e.g.its armature, or to otherwise respond to its state, in order to open orclose electrical circuitry in response to that position or state.Coupling may be by mechanical, magnetic, optical, electrical or otherwell-known coupling and the switch action itself may be mechanical,magnetic, optical, solid state or other well-known action. For a twostate (open/closed) relay the switching action may indicate the relayclosed or open or both as desired. For example, a switch may close a twowire circuit when the relay is closed, or may close a two wire circuitwhen the relay is open, or may include a three wire circuit with acommon, first wire and second wire with the switch closing the common tofirst wire circuit with the relay in a first position (e.g. closed) andclose the common to the second wire circuit when the relay is in anotherposition (e.g. open).

Relays may incorporate more than two positions or states, e.g. the open,latched open, closed, latched closed of one type of latching relay, andthe position circuit 79 may be configured to indicate all or a portionof the possible positions or states. Additionally, as discussed hereinthe relay 34 may be replaced by or augmented with other load controlfunctions, circuits or devices, for example such as a circuit breakercapability or an electronic current limit with or without a switch, andthe relay position circuit 79 may be configured to indicate suchoperation(s). For example, 79 may indicate breaker open, breaker closed,breaker tripped open in response to excessive current, or 79 mayindicate relay open, relay closed, relay closed with a first currentlimit, relay closed with a second current limit. The relay positioncircuit 79 may also be combined with other operations as desired, forexample the relay position 79 and current sense 23 d may be combined toreport to the microprocessor 37 over a shared or common communicationschannel. As another example the relay position 79 may be shared by arelay and a separate circuit breaker with 79 reporting relay open, relayclosed and breaker tripped conditions (note it may be possible for thebreaker to be tripped or closed while the relay is open or closed). Theselection of particular circuit(s), action(s) and coupling(s) to fit aparticular load and application will be well known to the person ofordinary skill in the art from the teachings herein and may be resortedto without departing from the spirit and scope of the invention asclaimed.

Various circuit connections 82 for connecting the 24 VAC supply from 81,24 VAC relay control, relay position and current circuits to 80L areprovided and it is desired that these connections be selected tofacilitate installation of the sections via low voltage wiring, e.g.screw terminals, punch terminals or the like. Accordingly, theimplementation of 80H may be performed with many off the shelfcomponents, e.g. a U.L. approved class 2 transformer and relay mountedin a U.L. approved enclosure (which may be the air conditioner housing)and in a large number of air conditioners and other loads the relay andtransformer are already present such that only 80L needs to be added toprovide a controllable load 48. The low voltage portion 80L may then beinstalled nearby the load, but in a location convenient to theinstaller, for example mounted in a waterproof plastic case mounted tothe outside of the load housing or an adjacent building wall. In such aninstallation the connections from the load housing (or 80H) to 80L maybe achieved by use of an 8 conductor cable such as common 20 gaugethermostat wire. If the current transformer and relay position elementsare not needed, such as in many air conditioners, a 4 or 3 wire (oneside of the 24 VAC line will usually be common) thermostat cable may beused. Other AC or DC voltages may be utilized as well.

FIG. 15 section 80L includes a battery and charger circuit 74 to receivethe AC (or DC) voltage from an external source. In this example powersupply 81 serves as the external source, however power may be receivedfrom other sources as desired including via one or more wiredcommunications link. The 24 volt AC power is preferably also madeavailable to external devices via connections 82, and shown in thisdrawing as being used to control relay 34 via relay 83 and dashedconnections. Connections 82 which are preferred to be readily available,low cost and easy to use terminals and can for example be spade lugs,screw, press fit or quick connect terminals and may be assembled on openor enclosed terminal blocks. The battery and charger circuit 74 providebackup (DC) power 75 with microprocessor 37, wireless link 29 k havingantenna 76 (which may be internal or external to 80L), user interface 77and other circuits if desired, powered thereby. As with 74 of FIG. 14 aswitching power supply may be incorporated to provide multiple output DCand/or AC voltages as desired including power 84 to external connectors82.

While DC voltage 75 could be coupled to external connectors, it ispreferred that 84 be a separate DC output which is isolated from 75 inorder to protect 75, and the circuits it powers, from any adverseeffects which would be experienced if some external device failed in ashort circuit mode. In that event, power 84 might be shut down due tothe short circuit however 75 will continue unaffected. In the embodimentof 80L it is desired for reasons of installation flexibility that thesection includes a relay 83 which is controlled by the microprocessorand that the relay contacts are made available for external connectionand further that one or more of these connections be current limited orotherwise protected, in this instance shown by the use of 86 in therelay swinger circuit. DC voltage output(s) 85 from the microprocessorcircuit are also preferred to be made available for external connectionas shown, including protection 86.

For example, a microprocessor output may control a 12 volt DC supplyconnected to a screw terminal as shown by 85. Connections to externalconnection terminals, if not otherwise protected (e.g. as with class 2or 3 transformers) are preferably made via protection 86. Positivetemperature coefficient (PTC) resettable fuses are particularly usefulchoices for such protection but other means of protection including forexample current limiting circuits and devices, standard or otherautomatically resettable fuses or standard or automatically resettablecircuit breakers may be utilized if desired. In this fashion 80L may beeasily connected to 80H. 80L may as well be connected to various typesof systems and devices by providing DC and/or AC voltage sources as wellas normally open and normally closed relay contacts via screw terminalor other convenient types of connections 82. As shown via dashed linesbetween 80L and 80H in FIG. 15 these connections may be configured tocontrol the coupling of power to the load in 80H.

In addition, it is desired that the type and number of circuits andtheir connections 82 be chosen in order to facilitate commonality ofconnections between various models of high voltage and low voltagesections and in particular any circuits unused in a particularinstallation be designed such that having any unconnected terminal(s)will not have an adverse effect on the system. For example if a highlyfeatured low voltage section 80L provides for a number of connections 82to the high voltage section 80H and external devices such as 81, and itis desired that if a basic high voltage section 80H is connected to that80L, any unused circuits (or circuits which are intended to be used butare miswired or defective) are automatically detected by 80L such thatthey are reported to the user interface and/or load control, disregardedor the circuits are otherwise designed to accommodate the lack ofconnection.

One example in understanding this feature may be given in respect tocurrent sense 23 d. If the low voltage section 80L is designed to accepta connection to 23 d but the high voltage section 80H is a basic modelwhich does not include a current sense then 80L is desired to operate todetect the lack of a connection to a current sense and operate withoutit. This operation may be achieved via sensing the voltage, resistanceor other characteristic (for example such as impedance or capacitance)between the connections and detecting a high resistance if there is noconnection to 23 d and a known resistance if 23 d is connected. Themicroprocessor circuit 37 may operate to perform this sensing or torespond to other sensing circuitry. Multiple types of current sensedevices may be detected and accommodated in this fashion, assuming eachtype has a different resistance or other characteristic. Previouslypresent circuits which become disconnected, silent or otherwiseinoperative or suspect (e.g. because of unusual readings) may bedetected via the microprocessor circuit 37 and reported via the userinterface 77, via communications link 29 to load control 25 orotherwise.

Another manner of accommodating unconnected circuits is via circuitdesign of the particular circuit. For example, a resistor or othercomponent may be connected between two current sense connections on thelow voltage section 80L or the high voltage section 80H to ensure littleor no static charge or noise will build up on the circuits and thus zerocurrent will be sensed and reported in the microprocessor circuit 37 ifno current sense 23 d is connected. The resistor or other component mayalso be used to signify the presence of the current sense 23 d. If thecurrent sense circuit 23 d is connected the microprocessor circuit 37will eventually be able to detect or respond to a voltage on the circuit(corresponding to a current flow in the load) when the relay 34 isclosed and thus detects that the current source is connected. Themicroprocessor circuit 37 may also detect or respond to a voltage on thecircuit (corresponding to a current flow in the load) and that voltage(load current flow) going to zero immediately after the relay 34 opensand know the current sense is connected. At initial installation orother times, the microprocessor circuit 37 may be caused to energizerelay 34 to determine if a load sensor is connected, or to energize analternative voltage or current circuit in the high voltage section 80Hto simulate a current flowing to the load and thereby detect if thecurrent sense circuit 23 d is connected, which may also be used tocalibrate the current sense circuit. These and other circuit operationsand/or designs may be incorporated at either or both ends of the circuitcommunications between the two modules or the connections themselves toallow detection of connected or unconnected circuits, effectivelycommunicating the configuration of one section or device to another.Microprocessor circuit 37 may also be programmed by an installer viauser interface 77 and/or communications link 29 to identify the presenceor absence of particular models, devices, features, options and thelike.

It is envisioned in the commercially valuable embodiments of FIGS. 14and 15 (as well as those of the of the preceding Figures) that for costreduction reasons the microprocessor circuit 37 will be configured toperform many of the functions and features described, with the relays 83and 34, current control 44, wireless communications link 29 k andassociated antenna, user interface 77 and battery and charger 74,current sense 23 d, and power supply 81 being separate circuits forreasons of their diverse physical and/or electrical requirements. Forexample, relay 34 is required to handle high voltages and currents whichwith present technology make it difficult to incorporate that relayfunction into the microprocessor circuit 37. In keeping with theteachings herein, the load control 80 (or 80H and/or 80L) of FIG. 14 or15 and their individual circuits and functions may be configured by theperson of ordinary skill in the art to fit particular needs and sets ofrequirements It is envisioned however that in the practice of theinvention for particular applications and their requirements thatcombining various of the individual circuits and functions, and/orfurther separating of combined functions, removing features andfunctions as well as adding additional features and functions may beuseful. Additionally, for higher volume applications it is envisionedthat ARM and RISC types of processors, along with embedded designs andeven ASIC devices will become attractive technologies for implementingportions of the present invention.

FIG. 16 shows a simplified diagram of a further load control embodiment88 which is coupled to power from the genset which is supplied via atransfer switch and controlling the power supplied to a load 16 with acurrent control 44. The load control circuit 25 c, senses one or moreparameter of the power, in this example the A.C. power frequency viaconnection 87 as well as the current drawn by the load via a currentsense 23 d and controls the current delivered to the load via control ofcurrent control 44. Load control 25 c may also sense the voltage,distortion or other parameter of the power via 87 and incorporate thosemeasurements into the control. In this embodiment the load controlcircuit 25 c will operate to sense the power frequency (and/or voltageor other parameter) via 87 or otherwise and when the load in the gensetnears or enters an overload condition the power to the oven will bereduced or limited or even turned off, thereby preventing or removing agenset overload.

FIG. 17 shows a simplified diagram of a further load control embodiment89 which is coupled to power from the genset and connecting ordisconnecting the power supplied to the load via switch 34. The loadcontrol circuit 25 d senses one or more parameter of the power, in thisexample the A.C. power frequency (and/or voltage or other parameter) viaconnection 87 and controls the connection of the load. In thisembodiment a clothes dryer 17 is shown as the load by way of example andit will be recognized that if the voltage to the dryer were to bereduced by any substantial amount the electric motor which providesrotation of the dryer drum could overheat and be damaged. Otherwise, anyslowing of the electric motor caused by reduced voltage (even forsynchronous motors) could cause reduced airflow through the dryer andcreate a fire hazard. For these reasons it is more desirable to simplyswitch the dryer on and off via switch 34 than to attempt to limit thecurrent supplied to the dryer. The embodiments of FIGS. 16 and 17 mayoperate with power inputs from any power source known in the art inwhich one or more parameter of the power changes as the load on thepower source approaches maximum or enters overload, or a novel powersource in which one or more parameter of the power is controlled inresponse to the load thereon as will be described in more detail below.

FIG. 18 shows a more detailed diagram of the preferred load controlcircuit 25 c having a transformer 81 which is connected to the A.C.power via 87, a frequency measurement circuit 90 responsive to the A.C.power via transformer 81 and supplying frequency information tomicroprocessor 37. A power supply 74 receives low voltage A.C. powerfrom transformer 81 and supplies power to the circuitry of 25 c asnecessary. A user display 91 and user input 92 allow a user tocommunicate with the microprocessor 37 and a timebase 93 provides timeinformation to 37. A current measurement circuit 95 is responsive to acurrent sensor 23 d (not shown in FIG. 18) to provide load currentinformation to 37 with 37 operating to communicate with a switch and/orlimit driver circuit 94 to control the associated load. Microprocessor37 may also be configured to sense one or more parameter of the powerfor example such as the voltage at 87 either directly or from the outputof transformer 81 by using a voltage measurement circuit or otherwise aswill be known from the present teachings. It will be recognized that thecircuit may also be used as the load control 25 d and if desired mayeliminate or not utilize the current measurement circuit 95.Additionally, the circuit of FIG. 18 may also be utilized to control aparameter of the power for example such as by control of the frequencyand/or voltage of the A.C. power supplied by the genset in response tothe load on the genset as will be described further below.

Load control circuit 25 c may include a transformer 81 coupled to theA.C. power from the genset (e.g. which is supplied for a particularload) and to provide a safer low voltage for use by the circuitry. Inparticular it is desired that 81 be the aforementioned Class 2 (dry) orClass 3 (wet) transformer having an input voltage matching the gensetvoltage (e.g. 120 volts) and an output voltage of 24 volts as is wellknown in the genset industry. Other types of transformers may beutilized as well to fit particular needs. Power supply 74 is preferredto receive the A.C. voltage from the transformer and provide batterybacked up D.C. power out at a voltage, or voltages, utilized by thecircuitry of 25 c. In particular 5 or 3.3 volt outputs for powering thevarious circuits 90-92, 37 and 93-95 are desired.

A microprocessor circuit 37 is provided which operates to interface withthe circuits 90-92 and 93-95 to receive A.C. power frequency informationfrom frequency measurement circuit 90, optionally receives parameterssuch as voltage information from 87 or otherwise, receives timebaseinformation from timebase 93 (which may be provided by the crystaloscillator for the microprocessor clock and internal circuitry), currentinformation from current measurement circuit 95, and user informationfrom a user input 92, and to provide messages to the user via userdisplay 91 and control of the current control 44 of FIG. 16 or loadswitch 34 of FIG. 17. Optionally the circuitry may provide control ofthe speed of the genset engine or voltage of the generator output (notshown) via an electronic switch/limit driver circuit 94. User display 91may be of any type well known in the art suitable to display messages tothe user as taught herein and may also be utilized to facilitate userinput, to display operating conditions, provide fault warnings and todisplay other messages as will be known to the person of ordinary skillfrom the teachings herein. User input 92 may be of any type well knownin the art suitable for input by the user as will be known to the personof ordinary skill from the teachings herein. User display 91 and userinput 92 may be combined if desired, e.g. via a touchscreen.

It is preferred that 25 c be mechanically configured in order that itmay be physically located next to current control 44, load switch 34,the controlled load, e.g. 16 or 17. In particular it is desired that itbe incorporated with those components within their enclosures for easeof installation. In particular, by incorporating the elements as shownin FIGS. 16 and 17, or within the load, or within the genset theadditional wiring necessary for connection of the load, or the genset iskept to a minimum. In this fashion control of individual loads may beprovided without the need for a more complex load control communicatingvia links to a plurality of load limits and load switches thus providingflexible and cost effective overload protection, but at the potentialcost of accuracy due to reliance on power parameters measured at thatload as compared to the embodiments of the earlier figures which mayoperate with accurate measurement of the total power output of the powergenerator.

In operation 25 c or 25 d is preferred to monitor power parameters forexample the A.C. frequency (and/or voltage) of the supplied power andcontrol the load accordingly. In particular the characteristics of thefrequency (and/or voltage) versus load are preferred to be programmedinto the microprocessor either at manufacture or by the user duringinstallation in order that the microprocessor may know if the load beingsupplied by the generator is below overload, near overload, slightlyoverloaded, significantly overloaded or highly overloaded. It is alsopreferred that the microprocessor be programmed in order to know thetype of load being controlled and its priority and to control the load,via driver 94 according to the amount of overload, the time that amountof overload has existed and particular characteristics of the load.

As one example if the genset is nearing overload the load controlcircuit will operate to prevent a low priority load from being connectedto prevent additional loading of the genset, or to disconnect or limitthe current supplied to a low priority load in order to reduce the loadalready coupled to the genset. As another example if the genset suddenlybecomes significantly or highly overloaded a low priority load would beprevented from being connected or immediately disconnected if it isconnected. Lower priority loads are preferred to be connected only whenthe genset is below overload, or if a high priority load is relativelysmall it may be connected when the genset is only slightly overloaded.If already connected when the genset goes into any overload conditionthe higher priority load would be disconnected only after a time delay(set by the user) in order to give other lower priority loads time to bedisconnected by their controllers. In this respect it may be recognizedthat a plurality of FIGS. 16 and/or 17 load controls may be utilizedwith each one programmed with a different time delay in order that thelowest priority load is disconnected first, thus avoiding the prior artproblem of disconnecting all lower priority loads simultaneously. Inaddition, a low priority load may be disconnected or left unconnectedwith no attempt to reconnect the load being made until the genset isbelow (or well below) overload thus preventing the prior art problem ofblindly connecting low priority loads. Of course, multiple driver 94and/or current measurement circuits 95 may be incorporated within loadcontrol 25 c in order to monitor and control multiple loads according tothe teachings herein.

Additionally, in 25 c or 25 d current measurement 95 may be utilized tomonitor the current drawn by a load and to control that or other loadsaccordingly. For example, if the load is one that should not beconnected immediately after is disconnected, such as an air conditionercompressor, 95 may be utilized by the microprocessor 37 to determinewhen the load was last drawing current and a timer used to preventreconnection before it is safe. It is preferred that the microprocessor37 have stored parameters pertaining to at least the frequency at whichthe genset is exhibiting an overload, and may also have storedparameters pertaining to time durations versus overload and parameterspertaining to the load being controlled, priorities and desired systemoperation. The stored parameters may be stored at the time ofmanufacture, at the time of installation or later, e.g. via user input92, or may be determined by the microprocessor during operation andstored for future use.

A novel feature of load control circuit 25 c is that it may be utilizedto control one or more parameter of the power output from the genset inorder to convey load information to load controls 88 and 89. For examplethe speed of the genset engine and thus the power frequency, and/or thealternator control and thus the voltage, of the output A.C. power may becontrolled as a measure of the loading of the genset. In this fashionthis reasonably accurate measure is coupled to individual load controlsfor control of those individual loads without the need for separatecommunications therebetween. In this fashion the prior art need to hardwire communications from the transfer switch to the load contactor iseliminated while at the same time improving the accuracy of overloaddetection. This capability is particularly useful with typical gensetswhich have an engine sized such that the alternator will overload beforethe engine slows down, but is also useful for gensets where the enginewill slow down first. The current supplied by the genset is preferred tobe sensed with a current sense such as 23 d which is coupled to currentmeasurement 95. That current is then utilized by the microprocessor 37to generate a control signal (or a plurality of control signals) viadriver 94 which is coupled to the genset engine's engine control module,or otherwise to the throttle of the engine in order to control theengine speed and thus the power frequency by know amounts in response tothe load.

The driver 94 or another driver may also be coupled to the alternator tocontrol the voltage output if desired, either in addition to frequencycontrol or in place of frequency control. For example, if the genset isat 95% of its rated load the power frequency can be lowered from asteady state 60 Hz to for example a steady state 59.5 Hz. If voltageadjustment is used the voltage may be lowered from a steady state 120volts to 115 volts. These are relatively small amounts but may bemeasured by frequency measurement circuits 90 and/or voltage measurefunction of 37 in individual load controls to signify that the genset isnearing full output capability. It is preferred that a microprocessor 37which is utilized for such frequency and/or voltage control have storedparameters related to current levels relative to overload and desiredfrequency and/or voltage relative to current or loading levels. Thestored parameters may be stored at the time of manufacture, at the timeof installation or later, e.g. via user input 92, or may be determinedby the microprocessor during operation and stored for future use.

If the genset goes into overload, for example 105% of its rated load,the microprocessor can then operate to adjust the frequency and/orvoltage to a different amount, for example 59 Hz and 110 volts. Thiswill let the individual load control circuits know that the genset isslightly overloaded in order that they can control their loadsaccordingly. For example, at this value one or more low priority loadscan be limited or disconnected, preferable in sequence according totheir priority with the lowest priority loads being disconnected first,until the genset load returns to an acceptable amount which would resultin the genset control returning the frequency to 60 Hz and 120 volts.For very low loads the frequency could also be increased, for example ifthe genset is only loaded at 50% the frequency could be set at 60.5 Hzand the voltage set to 125 volts.

Of course, setting engine RPM and/or frequency accurately in response toload is useful in the preferred embodiment and the microprocessor 37 mayoperate to sense that RPM indirectly by monitoring the power frequencyvia 13 and sense voltage via its voltage circuit. In this fashion highlyaccurate settings may be established with any inaccuracies being sensedand removed or reduced via adjustment of the control provided to theengine via 90. It is noted that the use of frequency measurement circuit90 and voltage sensing circuitry in 37 are provided by way of exampleand one of ordinary skill will know to practice the invention with manyvariations of circuitry and microprocessor types 37. For exampleseparate voltage and frequency circuits may be utilized with theiroutputs coupled to 37, a combined voltage and frequency circuit may beutilized with its output coupled to 37, or for some microprocessorshaving analog input capabilities, e.g. one with an analog to digitalconverter, a low voltage version of 87 (e.g. the output of transformer81 coupled via a resistor divider or otherwise) may be coupled to 37 asknown in the art and any desired power parameter or combination thereofmay be determined directly thereby.

It is preferred to accurately control engine RPM and many gensetsalready incorporate a frequency control circuit so that the driver 94should be coupled to that frequency control instead of the enginecontrol module or throttle. It is also possible to modify some frequencycontrol circuits to accomplish a known relationship between powerfrequency and genset load without the use of the full circuitry of 25 c.It is still further possible that the voltage regulator or othercircuitry of the alternator which controls output voltage may be coupledto be controlled via 37 utilizing a driver circuit 94 or otherwise orthat that control circuitry may be modified to provide a knownrelationship between output voltage and power without utilizing the fullcircuitry of 25 c as will be known from the teachings herein. Further,both voltage and frequency control of a genset may be utilized to conveyload information to load controls.

Whether there is a dedicated control of genset frequency or voltage inresponse to the load, or merely a simple engine speed or alternatorcontrol without any controlled response to load (e.g. via a circuit 25c), it is possible for the microprocessor of a load control 25 c tooperate to infer load conditions by measurement of one or moreparameters of the output power. One or more of frequency, voltage,distortion and noise changes which take place as loads are connected anddisconnected as previously described may be utilized. Performance of agenset generally decreases as it approaches overload and that decreasedperformance often results in measurable changes in one or more parametersuch as frequency, voltage, distortion and noise which may be utilizedto sense loading. As an example, when the genset is lightly loaded arefrigerator motor starting might cause the frequency to only dip 0.1 Hzfor 3 seconds and when the genset is near maximum load the same motorstarting would cause a 0.3 Hz dip for 3 seconds. The voltage might dipone volt if lightly loaded and 5 volts if near maximum. Distortion, suchas sine wave distortion of the power might not increase at all iflightly loaded but jump to 5% if near maximum output and noise mightincrease by 10 Db.

More generally, for a particular genset the parameters such as frequencyand/or voltage variations of the output power may be known to increasein size or duration as the genset approaches full load or entersoverload conditions. By monitoring these parameter changes which takeplace with the somewhat random normal load changes during operation themicroprocessor may estimate the amount of load. In particular byutilizing the aforementioned circuitry to perform current and voltagemeasurements combined with either a known connection of a load such asan air conditioner compressor or the somewhat random changes of normaloperation it will be possible to estimate the total load on the genset.Such monitoring is particularly useful for controlling large loads whereit is undesirable to allow those loads to impart large step loads to analready heavily loaded genset.

The above described feature of determining genset loading from outputpower parameters such as the frequency, voltage, distortion or noiseresulting from a particular load change is particularly useful whenmultiple loads are controlled by a given load control circuit. In thisfashion differing loads of differing priority may be controlled tooptimize powering those loads without overloading the genset, accordingto information about the loads, genset, priorities and desiredperformance of the system as programmed in the load control operationtime of manufacture, or manually or automatically at time ofinstallation, or later via automated monitoring of power parameters ormanually via the user display and input.

One example of an embodiment of the invention described above which willfind particular usefulness in modern homes and businesses is theincorporation of the load control 25 b and various communications linkswithin, or combined with, a more extensive home control system in orderto provide flexible backup power in the event of a power grid failureand to manage the cost of power consumed by the loads. It is preferredthat the a home control system (or part of the system) willautomatically manage the operation of the home as is well known in thehome control industry, e.g. to set temperatures, provide home operatingmodes such as away and occupied, operate lighting and entertainmentappliances, operate door locks and control access to the home, monitorthe home for failures and intrusions, all of which may be performedautomatically or as commanded or programmed directly or remotely by thehome owner. U.S. Pat. No. 7,379,778 describes one such home controlsystem. Of particular advantage in such a combination is the relativeease of adjusting load priorities. For example, if the home control isprogrammed for unoccupied operation various loads such as hot waterheaters, air conditioners, ovens and other devices which are primarilyused for comfort of the occupants can be assigned low priorities.

Additionally, the present invention is desired to be incorporated in orotherwise combined with the home (or business) control system to includenot only control of power consumption during times of limited availablepower or failure, such as when the grid power goes into brownout orfails, but also to facilitate reduced waste and lowered cost.Additionally, the incorporation in a home control system allows theinvention to respond directly or remotely via telephone, internet orother communications link(s) as described herein to provide the home (orbusiness) owner with information about the home, including grid,generator and load operations and to additionally respond to desiredpriorities for powering devices and otherwise operating the home (orbusiness). In particular as explained above several types of powersources generate excess heat in their operation, which excess heat maybe utilized under control of load control 25 b to provide heating, e.g.water heating or radiant heating as requested by the automation system.

Exemplary Small Backup Power System Embodiment

An embodiment of the invention as used with small backup power systems,which is believed to achieve a commercially desirable tradeoff ofperformance and cost is given by way of example. This embodiment isdescribed with respect to FIG. 8 as used in a home and is explained inmore detail below and may operate to prevent overloading of one or moreof the power sources 12, 13 and 50 and in particular may be utilized toallow the use of distribution panels having amperage ratings higher thanthe service or backup power source rating. The explanations below maydepart from the more general explanations given above under thedescription of the preferred embodiment in specific areas.

This small backup power systems utilizes a backup generator which isonly capable of providing power for part of the maximum possible loadwhich can be connected when the power grid fails and the total load mustbe controlled to prevent an overload. With some prior art systems suchas that of FIG. 2 this limit is hard wired, that is, only certain higherpriority loads are connected to the backup generator and those lowerpriority loads which are not connected simply go without power. In otherprior art systems such as that of FIG. 3 certain lower priority loadsare connected but are all immediately disconnected if the frequency ofthe AC power from the generator drops as a result of an overload. Thosedisconnected loads are then reconnected after a time delay withoutregard to whether the generator will be able to power it and thus a highprobability that another overload may be created.

Neither of these systems is capable of a high degree of utilization ofthe power available from the generator with high overload immunity, inthe first low priority loads are never powered and the generator may runwell below its load capability and in the second a low priority load maybe powered part of the time but when it is disconnected after anoverload it will not be reconnected until after a time delay which isunrelated to the generator's ability to power that load at that latertime, i.e. it is blindly reconnected which may result in an instantoverload and possible damage or circuit breaker tripping. In addition,when utilizing prior art gensets (i.e. those which do not have an activecontrol of frequency in response to loading) and relying on powerfrequency as a measure of overload the detection of overloads has lessthat desired reliability in many cases.

Recognizing the above faults, this embodiment of FIG. 8 controls thetotal load presented to the generator 13 to connect some or all loads16-19 & 48 according to a priority, which priority may be changedmanually or automatically. In particular the load control 25 b isprogrammed with parameters pertaining to the power sources and loads,which parameters are necessary to achieve the desired mode(s) ofoperation of the system. For example, 25 b is preferred to be programmedwith the maximum current output of the solar panel 50 (if utilized), themaximum current output of the generator 13, the current output foroptimum efficiency of the generator 13 and the current drawn (e.g. load)by each load which 25 b is capable of controlling (e.g. connecting). Agroup of high priority loads 19 such as selected lights, home controls,alarms, food storage appliances and the like which are desired to bepowered whether the home is occupied or not are always connected andreceive power from the transfer switch 47 upon loss of grid power, itbeing preferred that these high priority loads are selected to ensurethat they are not capable of overloading the generator at their maximumcurrent demand.

When operating with the solar panel 50 (if provided) and/or generator 13it is preferred that load control 25 b operate a) to prevent overloadingthe generator 13 or solar panel 50 by preventing or limiting theconnection of loads which would cause an overload, b) to immediatelycure an overload by promptly disconnecting or limiting one or moreconnected load, c) to maximize efficiency of solar panel 50 and/orgenerator 13 by allowing operation of loads which the generator and/orsolar panel are capable of powering when they are operating below theiroptimum capability, d) to alert the home owner that power is notavailable to power one or more particular device(s) which the home ownermay wish to operate and e) allow the home owner to decide what to turnoff (or limit or leave off) in order to prevent having a device (andpossibly several others) turned off shortly after the desired deviceturned on due to an overload. Selected loads that may but do not need tobe connected are preferred to be connected when the generator and/orsolar panel is operating below its optimum capacity or efficiency inorder to provide operation closer to that optimum. These operations areperformed by the load control 25 b in response to the loads currentlyconnected to the solar panel 50 and generator 13 as measured via currentsense devices 23 a and 23 c and the herein described stored parametersfor the generator and solar panel, as well as stored parameters forloads which can be connected or otherwise controlled by 25 b.

When the generator is operating well below optimum, either duringexercising or during outages, an increase in the efficiency of theoperation is achieved by connecting lower priority loads such as batterychargers, water heaters, heat and air conditioning units. Accordingly,different modes of operation may be assigned to the backup system by theuser via 21 or otherwise, with the user selecting priority of connectionof the loads and the system automatically connecting and disconnectingloads to best achieve the priority based modes of operation undercontrol of load control 25 b operating in conjunction with the otherelements of the load control system shown in FIG. 8.

Importantly, the priority of one or more load(s) is preferred to bechanged automatically, or by the user if needed with the changedpriority being permanently stored, at least until it is updated, for anamount of time selected by the user, or for other conditions selected bythe user. For example, to cook a meal which has already been startedwhen the grid power goes off. The load priority for the oven may bechanged automatically by 25 b recognizing that the oven was in use whenpower failure occurred, with the priority of the oven being returned toits previous value when the cooking ends as sensed by the current beingdrawn by the oven or otherwise. Alternatively, if the priority is notautomatically changed by 25 b the user may assign a higher priority tothe oven for a time period such as an hour to allow completion of thecooking, or in response to the condition of the oven no longer utilizinga large current for 15 minutes indicating the cooking is completed.Thermal sensors may also be utilized to provide oven temperature to 25 bas part of the miscellaneous devices 21, which temperature may beutilized to set priority.

Priorities may be automatically changed, temporarily, permanently orrepeatedly in response to environmental or other conditions via 21 orotherwise. For example some lights are more important at night than inthe daytime and heating is more important when it is cold outside thanwhen it is hot, but this importance is tempered by whether or notanybody is home and thus priorities for such items are preferred to beset at a first value when the home is not occupied and/or duringdaylight hours and a second value when the home is occupied and/orduring night hours. As another example a temperature sensor may beprovided for a food storage appliance such as a freezer, refrigerator orwine cooler as part of 21 and if the temperature should approach adangerous level (high or low) that food storage appliance can be made ahigh priority until a safer temperature is reached. If the problem ofthe food appliance approaching a dangerous temperature occurs oftenduring power loss events its priority may be automatically changed to ahigher priority by 25 b whereas the priority may be automaticallylowered if the problem infrequently or never occurs. Such automaticchanges will serve to adjust operation to a more optimum condition.

Decisions can also be aimed at efficiency. One substantial considerationwhich can be utilized is the cost of providing power from the grid vs.cost from the generator, for example for a homeowner having one or moreelectric vehicle. If power can be obtained from the electric utility orelsewhere at lower cost during certain times, for example during thenight, the load control can be utilized to control loads in a manner tobest take advantage of the lower cost power. Load control 25 b mayreceive the cost of grid power at various times and the cost ofgenerator fuel (e.g. natural gas) automatically via the internet orotherwise and calculate the best time to charge the vehicle's batteriesfrom the grid or alternatively from the generator even though grid poweris available, depending on the cost. The load control 25 b may also takeinto account the need to exercise the generator and delay batterycharging until an upcoming scheduled exercise, advance the exercise timeonce to charge the battery or change the exercise time schedule toaccommodate the home owner's changing vehicle usage.

The load control is preferred to utilize intelligent timing forconnecting and disconnecting loads to one or more power sources in orderthat the total load on any one power source is kept at or below themaximum output capability of that source, or alternatively at or near anoptimum efficiency level, which may be at or below the maximum outputcapability. It is preferred that at all times the home owner has theopportunity to interact with the load control processor in order tofacilitate any out of the ordinary power needs the home owner may desireor require and which are not automatically provided for by the loadcontrol. For example, the home owner may choose to turn off an airconditioner or vehicle charger for 30 minutes in order to allow normallylow priority clothes dryer to be used. As another example the home ownermay want to limit the current supplied to an oven (causing the heatingelement to be on for longer periods of time) to allow an air conditionerto be used.

More generally, the present invention described herein may also beutilized to communicate with a power utility to allow that utility tomanage power consumption, for example to cause partial or total removalof loads from the power grid as the utility deems desirable or necessaryduring times of high power consumption, lack of grid capacity or gridfailure. The power company may notify the load control of possible orscheduled events pertaining to the supply of power from the grid, e.g.poor power quality (i.e. power not meeting specifications set by forexample the utility, the home owner or a regulatory agency) or rollingblackouts. The load control will then cooperate with the utility toaccomplish the desired degree of power consumed from the grid.

It may be desired that the utility company may interact with the loadcontrol to negotiate sending power to the grid from one or more powersources or loads e.g. during times of peak load. For example, the powercompany could request that the load manager send power from the powersources 13, or 50 or from the battery 68 via inverter 67 (FIG. 11) orthe like into the grid. The load manager may be configured to negotiatepricing with the electric utility for the power which it wishes to bedelivered. In such negotiations the load manager is preferred to takeinto account the cost of power available from various sources which areavailable to it to transfer power back to the grid.

FIG. 19 shows a still further embodiment of a novel load control andnovel transfer switch for use in small backup power systems andincorporates many elements the same as or similar to those describedabove as will be known to the person of ordinary skill in the art fromthe teachings herein. Details shown elsewhere herein are omitted fromFIG. 19 for clarity, however it will be understood that one or more suchdetails may be practiced with this embodiment. The embodiment of FIG. 19is preferred to be utilized in systems which have two separately meteredpower input circuits 104 and 106 which are provided to the same powercustomer, either or both of which may fail or not meet an acceptablelevel of quality, thereby creating a desire or need to use of backuppower from source 97. The novel arrangement of FIG. 19 will findparticular and novel use with inputs 104 and 106 having unequal powerratings as will be described further below. These power inputs 104 and106 may for example be provided from the same power grid connection,from different substations of the same power grid, from different powergrids or more generally from any two power sources suitable forproviding power to small backup power systems. In particular, thepreferred embodiment of FIG. 19 load control and transfer switch will befound useful in systems which, unlike the prior art, utilize separateand unequal power inputs with separate metering. It is preferred thatthe actual metering circuits of the dual meter comprise electronicmetering e.g. a processor receiving voltage and current information fromsensors such as for example metallic voltage contacts and currenttransformers and calculating power in units corresponding to those usedin billings, and if desired other power parameters as well.

Split utility service entrances having a single meter and two equallyrated service feeds are known in the art. As an aid to understandingthese systems, one may refer to what is perhaps the most common one usedin the U.S. which is described in U.S. Pat. No. 9,281,715 to Lim et al.The Lim et al. device receives and meters a single 400 amp feed from thegrid, and uses a splitter (30 of FIG. 6) to split the 400 amp feed intotwo 200 amp circuits. (Col. 1, II. 34-44.) The two 200 amp circuits willbe referred to herein as A1 and A2 for convenience in describing thedevice. As shown in FIG. 2, the A1 and A2 circuits are coupled tocircuit breakers 38 and 40, presumably rated at 200 amps each. Thecircuits A1 and A2 are further coupled to a corresponding 200 amp loadcenter (breaker) panels 11 and 12. From here the two panels distributepower in two separate power circuits to the various loads in the house.One of ordinary skill in the art will recognize that it is desirable towire the loads to the two distribution panels 11 and 12 in order thatthose loads will be roughly equal at times of high loading in order tomaximize use of the 400 amp service and prevent overload of one of thepanels. With a single revenue meter the loads may be wired to eitherpanel as desired to balance the loads.

For example, if the total of loads that the house is capable ofpresenting is 380 amps, it is undesirable to wire loads that can presenta maximum 290 amps to one panel and wire loads that can present amaximum 90 amps to the other as it could cause a breaker trip. Extendingthe example further, it would be contrary to the known use of two 200amp panels, as well as the Lim et al. teachings, to prevent such abreaker trip by using a 100 amp panel for the 90 amp load and a 300 amppanel for the 290 amp load. However, it will be known to the person ofordinary skill in the art from the teachings herein, that it is possibleand even desirable to use differently rated service entrances, a muchsmaller generator and transfer switching circuitry of unequal ratings.That is, the present invention is desired to operate with a plurality ofservice entrances of unequal size with correspondingly rated switchingcircuitry, and additionally to utilize a backup power source rated at athird size.

Lim et al. teaches away from the instant invention. Lim adds two 200 amptransfer switches 42 and 46 to the equal current split system (Col. 4,II. 54-67 & col. 5 II. 17-21) as well as a backup generator feeding asplitter with outputs coupled to the two transfer switches. (FIG. 2.)The Lim et al. system is used is described at col. 1, II. 61-64(underlining added) “Since the building normally receives the primarypower source the backup power management system is designed including asecondary power source that provides the same level of voltage andcurrent to power loads within the building.” In other words, that is theway Lim's system is designed, 400 amps total from the grid and 400 ampstotal from the backup. At col. 5, II. 8-11 (underlining added) Limconfirms “Like the power splitter 30 described previously the secondarypower splitter 54 splits the power supply from the secondary powersource 26 into two separate power outputs.” Lim et al. teaches that boththe 400 amp grid and 400 amp backup sources are split into two 200 ampoutputs. Presumably, in view of these Lim et al. statements, the circuitbreaker 52 is rated at 400 amps. Lim et al. does not teach or evenmention any other sizing.

Continuing now from the discussion of the prior art, in order to obtainparticular levels of performance, reliability and cost, the load controlprocessor circuit 99 of FIG. 19 may operate with desired ones ofcapabilities and features shown and described herein, including variousones of load controls 25 and the environmental, & Misc. Devices 21.While shown as a separate device in FIG. 19, it will be appreciated thatparts or all of the load control processor circuit 99, like otherportions of the invention, may be incorporated in or shared with variousbackup power devices, transfer switches, loads and home controllers. Theinvention will find further use with powering of fire pumps such asthose that pump water to fire sprinklers throughout a building where thefire pump must run despite any dangers to equipment such as for exampleoverloading conductors.

The National Electric Code (NFPA 70, 2017 Ed. or NEC incorporated hereinby reference), article 695 covers wiring of fire pumps, etc., andstandby generators used therefore, in some detail. In particular section695.3(B)(2) deals with overcurrent protection devices which includessubsection (1) “Overcurrent protective device(s) shall be rated to carryindefinitely the sum of the locked-rotor current of the largest firepump motor and the pressure maintenance pump motor(s) and the full-loadcurrent of all of the other pump motors and . . . ” (underlining added).That is a substantial departure from normal wiring practice where thewiring equipment must accommodate those as well as normal loads. Theinstant invention will be of benefit, allowing the fire pump system tobe powered from a second service entrance and/or via a second section ofthe transfer switch, with a backup power source. This and other criticaland emergency equipment wiring such as emergency lighting, elevators,smoke exhaust fans and the like (referred to herein as critical loads)will also benefit.

One of ordinary skill in the art will recognize from the teachingsherein that because the total of the critical loads may very well not beas large as the rest of the loads, using two service entrances ofunequal size as compared to one large entrance, is desirable. Inparticular, it will be understood that load control processor mayoperate such that non critical loads may be shed to provide power forcritical loads in the event power is being provided from the backuppower source 97. As just one example, using a dual transfer switch withcenter off capability where in an emergency the normal load part of thetransfer switch may be switched off leaving only the critical loads tobe powered. Codes permitting, this will allow the homeowner to use a 200amp service entrance per load calculations but yet accommodate another100 amp service for emergency loads which if used in the loadcalculations could require a 300 amp service, if it is even available.

The embodiment of FIG. 19, shows two physically separate serviceentrances with physically and electrically separate meters 96 and 98which measure the net power flowing from the respective power source totheir output 104 and 106. Such meters are often referred to as revenuemeters and measure watthours of power which flow from the utility,through the meter to the customer's load. It will be understood that theinvention described herein may be utilized with revenue meters and othersimilar types of meters which are not associated with billing. Theutility periodically reads the meter in order to bill the customer forthe power used. For purposes of this example power supplied to 96 and 98is described as being from the same power grid (e. g. the sametransformer and cable to the house). It will be understood that benefitsof the invention may be had with the same or different power sources.One of the service entrance's watthour meter 96 is used for normalbilling rates the other having a watthour meter 98 for time of service(TOS) rates. As practiced by some utilities, cheaper TOS rates willapply for usage at off peak hours, for example the middle of the night.It will be understood that the time of service meter 98 may be utilizedto facilitate the utility charging rates which are different from,either higher or lower (or in some systems at times the same as), thenormal billing rate charged for power provided via the first meter. Forexample, the utility may charge lower than normal rates for powerprovided via the TOS meter for off peak usage, higher for peak usage andnormal rates at other times. It will be understood that while only twometers are shown, any number of meters (and contactors in 100) may beutilized as will be apparent from the teachings herein. Also, contactorsin 100 may be controlled together or separately, or if more than two, incombinations. Particularly, it will be understood that contactors whichreceive power from the same power source, but delivered via differentmeters, are preferred (but not required) to be controlled together toprovide backup power when that power source fails.

Because the power required for the normal loads may be more or less thanthat required to power the TOS loads, the two watthour meters 96 and 98(as well as 96 a and 98 a discussed below) do not need to have the samecurrent measuring capability, response time, accuracy and/or precision.One meter may very well be different than the other and accordingly thecontactors may be of different size. For example, 96 (and 111) may berated at 400 amps and 98 (and 112) rated at 200 amps. Such ratings mightfor example support a normal billing house load with multiple airconditioners, an electric water heater and electric range and only two100 amp electric vehicle chargers on the TOS output. Because the TOSmeter only measures power supplied to two vehicle chargers, the metermay not only have a lower maximum current rating, it may also not needthe same quick response time and accuracy as is required for the normalloads which include a variety of devices. As another example, a meterwhich is used with critical loads such as an aforementioned fire pumpmay be designed to trade off response time for improved reliability.Alternatively, if the utility permits TOS billing for the multiple airconditioners, water heater, range they may be wired to the TOS circuitthus reversing the 400 amp and 200 amp meter and contactor ratings. Itwill be recognized that unlike the split service above, only utilityapproved devices can be wired to the TOS meter circuit.

FIG. 19 includes the backup power source 97 which may also be used toprovide power backup power costs less than normal and/or TOS power. Thebackup power contacts of 111 and 112 are electrically paralleled in 100with a single set of power terminals fed via 105. The load controlprocessor circuit 99, which may operate in a manner similar to 25 a and25 b, but with added capabilities relating to the multiple power inputs.99 also may incorporate environmental, user & misc. devices 21, as wellas those not shown to provide other capabilities, connections and thelike as discussed for 25 a & 25 b. It will be understood that theteachings of 25 a, 25 b and 99 are given by way of example and variousconfigurations and capabilities may be incorporated into or left out ofa particular load control as desired in order to practice the inventionto achieve a particular set of features and benefits for a desireddegree of cost for a particular application as will be known to theperson of ordinary skill in the art from the teachings herein.

The load control processor circuit 99 is preferred to operate to sensethe quality of power input in response to the power provided via 96(and/or 98), to determine the if the quality of the power meetsacceptable parameters and if not to control 100 to switch to backuppower by control of the contactors 111 and/or 112 when backup powermeets acceptable parameters. If neither meets acceptable parameters itis preferred that 111 and 112 be caused to switch to the off positionwith the load control processor 99 monitoring the grid and backup power.When one or the other power feeds meets acceptable parameters 99 ispreferred to cause 111 and 112 to switch to that power source, with gridpower taking priority if both are present. As taught above the offposition may be utilized to allow another power source to power loads.It is noted that other manners of monitoring, particularly indirectmonitoring, starting and connecting may be resorted to. For example, thetransfer switch(es) may monitor the grid power, start the backup powersource and make the transfer and 99 may then be responsive to thisactivity. Some backup power sources have built in power grid monitoringand will start themselves whenever needed and may also cause thetransfer switch to select the backup. Thus, the load control 99 maysimply be responsive to the transfer switch and/or backup power source.This has the disadvantage of 99 not directly sensing that grid power hasreturned which may result in another short outage when the backup sourceturns off and the transfer switch is returned to grid power.Nevertheless, the load control is responsive to the absence and returnof grid power, just not as efficiently as if it monitors the grid powerdirectly. Other combinations and sequences of operation to detectoutages and provide backup power may be resorted to from the teachingsherein as will be known to the person of ordinary skill in the art fromthe teachings herein.

Load control processor 99, may also be responsive to load monitor 23 einstead of or in addition to the backup power source, in order that 111and 112 are not switched to the backup power 97 until it is meetingdesired voltage and frequency parameters, for example meeting themanufacturer's specifications. Load control processor 99 may thendetermine when backup power source 97 is ready to provide power. It ispreferred that all of the controllable loads are turned off, disabled orotherwise configured to draw little or no power at the time grid poweris lost, or at least before the contactors 111 and 112 are switched toreceive power from 97. In this manner the instant load which ispresented to the backup power source at the switch time will be reducedas compared to not removing the controlled loads, and the load controlprocessor can then operate to turn the controlled loads on one or a fewat a time. In this manner the number of connected loads can be maximizedin response to the load parameters without overloading the backup 97 asdescribed herein.

The load control processor 99 operates in response to the loadmonitor(s) to determine the remaining available power which can beproduced by 97 without exceeding the manufacturer's maximum power outputspecification(s). 99 is preferred to respond to one or more of loadmonitors 23 e-i which respond to voltage and/or current from 97 todetermine one or more timely power output, for example such as amps,active power in watts, apparent power in VA as well as power frequencyin Hz. 99 may additionally determine amps, watts and/or VA drawn byindividual loads when powered by the grid via 96 or 98 and/or by 97.When determining power frequency and in particular for an internalcombustion engine powered backup power source, 99 may respond to asingle or multiple phases of output power, an engine position sensorsuch as a crankshaft sensor or camshaft sensor, or to a tachometerinstead of or in addition to the above. Responding in this method can beparticularly useful in determining the engine speed which for a directdrive alternator is directly related to power frequency.

Because engine tachometers usually provide many pulses per crankshaftrevolution, it is possible to sense speed changes in less than onecrankshaft rotation, giving a quick indication of an overload.Similarly, using ones of positive and negative zero crossings, peaks aswell as phases of output power provides a plurality of events percrankshaft rotation as compared for example to using a single zerocrossing. This is useful both to determine when the backup power sourceis up to speed after starting, but also to determine if its speed dropsdue to an overload. Load control processor 99 controls various loads inadvance of connection to attempt to prevent overloading the backup powersource 97, and also operates to disconnect one or more loads if thebackup power source becomes overloaded, for example such as by anuncontrolled load turning on or a user adding a load which causes thepower frequency to drop. It will be understood that overloads may becaused by uncontrolled loads.

The load control processor circuit 99 may also operate as describedabove with respect to 47 to disconnect one or more of 96, 97 and 98 e.g.by selecting the center off position of 100. This is useful for examplein the selection of entire groups of loads to connect and disconnect andalso to allow a smaller grid service to be used, such as in the firepump example above. The use of center off may be done for variousreasons which will be known to the person of ordinary skill in the artfrom the teachings herein, e.g. protection of the loads such as duringlightning storms or other severe weather, removing potential ignitionsources during gas leaks, leaving another power source (e.g. solar, windor battery) to power the loads, in the event of a fault, failure orother significant problem with one or more loads which cannot beotherwise disconnected, serious overload, fault or failure of 97, etc.This switching may help to prevent further problems, for example such asdamage to 97 and/or its uncontrolled connected loads.

If use of the center off position is contemplated, it is desired thatthe power to the load control processor 99 (which is normally providedfrom the output of the transfer switch) should be provided by a sourcewhich contains reserve power (e.g. a battery backup) and will continueto provide power to 99 for the longest expected duration of use ofcenter off. This may be aided by placing the load control processor in astandby or sleep operation which reduces power consumption while stillallowing it monitor for the return of grid power. Otherwise the power tothe load control 99 could be exhausted and the control's ability tosense the return of power from one or more of the power sources will beimpaired. Additionally, or alternatively as desired, power may be takenfrom the grid or both inputs to the transfer switch with the loadcontrol processor 99 being shut down, with attendant loss of function,in a manner that allows it to automatically start up on power return,thus helping to ensure that upon return of its power, the load controlprocessor can power up and resume its control operations. The sameprotection is desired to be used if the transfer switch is left in thebackup power position, particularly if the backup power can fail such aswhen a generator shuts down because of low fuel. Alternatively, the loadcontrol 99 may take power from the transfer switch output and when bothgrid and backup power fail, sense when its stored power is low andreturn the contactors to the grid position.

Moving now to the measurement of power supplied by one of the varioussources and power consumed by one or more loads, commonly, current ismeasured via a current transformer through which the current carryingconductor passes but is not in metallic, contact therewith. Voltage andfrequency are commonly measured via metallic contact with conductors. Itwill be understood that while 23 e-i are shown in FIG. 19 as having asingular location, the voltage, current and frequency may actually besensed at different physical locations as convenient. There is norequirement that voltage and current be sensed at the precise locationof 23 e-i or at the same location. Current may be sensed at onelocation, for example on an insulated cable via a current transformerand voltage at another, for example at a metal lug, buss bar, contactor,etc. (or fastener thereof) which the cable electrically connects to.Additionally, ones of 23 e-i may simply measure current and rely on aknown and relatively steady voltage to provide load parameters to 99e.g. current only, or use that voltage to determine watts or VA. Circuit99 may use one or more voltage inputs via connections such as 107, 109,125 and the transfer switch outputs, or use a known relatively steadyvoltage, along with current from one or more of 23 e-i to determinepower. 99 may also respond to individual power parameters, e.g. voltage,current and or frequency sensed at different points, and/or providedfrom the backup power source 97 via 107 in order to determine poweroutput.

Of course, the sources of measurement used to determine power sourceloading should be a reasonably accurate version of that at the output,or any error is otherwise taken into account. It is possible to measureboth voltage and current with or without electrical metal to metalcontact. For example, voltage may be sensed and measured via anelectrical contact such as used by a traditional voltmeter or withelectric field sense technology (without electrical contact). Currentmay be measured via a shunt (electrical contact) or without electricalcontact such as using a current transformer, Rogowski coil, Hall effectdevice, flux gate or magneto-resistive sensors. It will be realized fromthe teachings herein that 23 e-i may utilize either contact or noncontact sensing and measurements for voltage and/or current. Inparticular, it is envisioned that 23 e-i may utilize non-contactmeasurements at a convenient point, like output(s) of the transferswitch or the attached cables, by incorporating field sense of voltageand inductive sensing of current.

FIG. 20 shows an embodiment of a novel dual meter device operating witha novel dual transfer switch 100 configured for use in a system whichincludes both normal revenue metering 96 a and TOS revenue metering 98 aof current provided from the same power grid 12. As with other Figures,details have been omitted from FIGS. 20 (and 21) for clarity, andadditional capabilities, features and improvements may be practiced ifdesired as will be known to the person of ordinary skill in the art fromthe teachings herein. Dual meter 113 operates to receive power from apower grid 12 and provides two metered outputs 104 and 106 via dualmeter socket 113 a, that is, a single socket for a dual meter. The noveldual meter socket 113 a is part of the dual meter circuit not per separt of the dual meter 113, but rather mates to 113, or, stated anotherway the dual meter 113 plugs into the socket 113 a. The socket ispreferred to be physically mounted in an enclosure (not shown) whichfacilitates use of electrical raceway connections (e.g. conduit) toallow circuit connections between the socket 113 a and other devices.The enclosure comprises a cover (and possibly a meter ring) which isused to hold in place, tamper proof and security seal the dual meteronce it has been mated with the socket. The power flowing from the gridto each output is metered by a respective one of the watthour meters 96a and 98 a. The dual meter socket 113 a (sometimes called a meter baseand not to be confused with the baseplate) is preferred to be a singlesocket for the dual meter, to which the power grid is connected viacircuit 129 (FIG. 21), with the socket providing two power outputs via104 and 106, from 96 a and 98 a respectively.

Power from one or both of the power grid inputs 104 and 106 may bemonitored (not shown) by load control processor 99. Two transfer switchoutputs 101 and 102 are preferred to be monitored via load monitors 23 hand 23 i which are physically and electrically configured to sense powerflowing from outputs 101 and 102 respectively, the transfer switchfurther receiving power provided by the backup power source 97 via 105with 99 operative to enable backup power via 107 and to switch thecontactors of the transfer switch to connect the backup power to theoutputs as described herein. One of ordinary skill in the art willrecognize from the teachings herein that monitoring both the normal andTOS grid inputs 104 and 106 would seem redundant, however some utilitiesare able to control delivery of power via one or the other or both of104 and 106 using smart meters, the capabilities of which may beincorporated in 96 a and/or 98 a. It is envisioned that utilities willhave such capability during high load conditions for load shedding.Thus, it is possible to lose power on one feed but not the other ascontrolled by the utility. In this situation it is desirable to providebackup power for only the lost feed and keep the other connected to theutility. This of course will require separate control of the contactors111 and 112 via the load control processor circuit 99 (or a plurality ofprocessors).

It is believed that the novel transfer switch, self contained with twopower grid inputs provided via respective revenue meters, a singlebackup power input, two power outputs, one corresponding to each gridinput and an internal load controller, with the transfer switchcontrolling (e.g. via 99) both enabling (e.g. starting) the backup powerand switching thereto, as well as controlling external loads in responseto one or more load monitors, is an excellent combination of featuresand capabilities with low cost and ease of installation as is taughtherein. Additionally, including a load monitor on each output willprovide the capability of characterizing loads connected to eitheroutput when powered by either the respective grid input or the backuppower source. The inventive device can be used in a small backup powersystem which has a separate TOS revenue metering for various types ofTOS qualified loads such as electric vehicle and/or backup energystorage chargers, as well as normal revenue metering for other loads.

FIGS. 20 and 21, the utility and novelty of the dual meter 113 as wellas the novelty of the transfer switches 100 and 100 a may be furtherrealized when one understands service circuitry is sealed by the utilityand the NEC requires service circuitry to be protected in conduit, metalenclosures and the like, all of which must be watertight if usedoutdoors. Reducing the number of components is beneficial both to reducecomplexity and installation time and to reduce cost, among otherbenefits. Further novelty may be recognized from the fact that for amultiple unit dwelling such as an apartment building, and in particularthose with mechanical meters, an electric utility may wish to remove andreplace the meter with a locking cover and thereby disconnect all powersupplied to a particular apartment which is vacant or where the electricbill is seriously overdue. That in turn dictates that individual metershave for years been, and currently are, used to supply individual smallbackup power system customers.

By contrast, with the dual meter the two outputs are envisioned to havegreat utility serving the same customer and thus there is no need tophysically and electrically separate them for purposes of disconnectingpower. As used herein and in the claims, the term dual meter is definedas a device comprising a plurality of revenue metering circuitsphysically contained within a single case, the case comprising a coverand a baseplate and designed to provide electrical service to a singlecustomer of an electric utility via each meter output, the watthourmetering circuits being connected to meter blades protruding from thebaseplate and disposed to connect with jaws of a single dual metersocket. A dual meter socket may be enclosed in an individual enclosure,or may be incorporated in an enclosure with a service disconnect forexample such as 123 and/or a transfer switch 100 or 100 a and/or a loadcenter (not shown).

The two power outputs from 113 are coupled to a novel transfer switch100 a which switches both the normal billing feed and the TOS billingfeed, thus saving switch enclosure costs and space, as well asinstallation and wiring costs and time as compared to using two transferswitches. Transfer switch 100 a has two sets of contactors, but ascompared to two transfer switches of the prior art it is preferred toonly have one input for receiving power from backup power source 97,that input having terminals for single phase or multiple phase operation(instead of double that number of terminals for two separate transferswitches). Transfer switch 100 a also has an input for receiving normalrevenue metered power via 104, an input for receiving TOS revenuemetered power via 106. The single input connection for backup power tothe two separate transfer switch sections in the single enclosure ispreferred to be provided by a buss bar or other low cost connection foreach power phase. The contactors of the transfer switch 100 a may beimplemented with any of the devices described herein as well as otherscurrently known or which may later become known to the person ofordinary skill in the art to be suitable for the novel purposes as willbe known to the person of ordinary skill in the art from the teachingsherein.

As set out above, a transfer switch 100 or 100 a may be combined withones of a service disconnect e.g. 123 and load centers (not shown) in asingle enclosure to provide a device which has two service entranceconnections, a single backup power connection, a normal billing poweroutput and load center if desired and a TOS billing power output andload center if desired. It will be further appreciated that the servicedisconnect 123 may include breaker overload protection instead of or inaddition to each disconnect switch 123 a and 123 b, the breakers alsoserving as the service disconnect, which is particularly well suited ifbeing substituted and ganged to provide a common trip function. Thebreaker may be combined with a load center (breaker) panel, with thetransfer switch electrically disposed between the output of the servicedisconnect (breaker or switch) and the load center bussing. A breakermay also be provided in the single enclosure for the backup power inputfrom 105.

By incorporating load control and overload protection which is limitedto a known maximum size backup power device, the cost of the transferswitch 100 a may be further reduced because the internal bussing,wiring, contacts and the like may be designed to match that known sizerather than to match the size of the service entrance. For example, atransfer switch 100 or 100 a may be designed to accommodate a 400 ampservice entrance but only a 100 amp backup power source knowing that theload connections will be managed so as not to draw more than 100 ampsfrom the backup. Further, the transfer switch 100 or 100 a may havedifferent sized normal billing and TOS billing electrical paths, e.g.400 amps for the normal billing service which may include several highdemand loads like electric air conditioners, range and hot water heater.The TOS billing service may be sized for only 200 amps to power two 100amp electric vehicle chargers and the backup power circuit sized at 100amps. It should be recognized that these sizes are not required to be inany particular sequence, e.g. any of the power sources may be largerthan the other. When the backup power is capable of delivering enoughpower, and the connected loads are capable of consuming enough power tooverload a transfer switch input or output, care must be taken toprevent such overloads. The aforementioned 100 amp backup powerconnection will provide an efficient and cost effective arrangement. Itis believed that the advantages of providing a dual transfer switch withunequal electrical size capabilities has heretofore not been known,appreciated or utilized in prior art transfer switches having a maximumoutput current design when either input is selected.

This novel configuration is cost effective, easy to install, reliableand smaller for a given amperage as compared to using two separatetransfer switches. The benefits also including being able to use asingle switching mechanism for the separate transfer sections ifdesired, as will be seen in respect to FIGS. 23A-E (discussed below),using a single transfer switch controller circuit 99 instead of two (ormore), bussing of the backup power from the input to one switch and tothe other(s) thus eliminating terminals and wiring for each phase aswell as the associated enclosures, conduit, labor, etc. Because the twogrid power connections 104 and 106 are on the customer side of themeters, many electrical code jurisdictions will permit the separate setsof cables to be run through a single conduit from 113 to 100 a, thussaving installation time and cost.

Regarding the ease of installation, consider how the backup power source97 would have to be wired to both of the contactors if there were nointernal buss between them. Two cable sets (2 cables plus a neutral forsingle phase and 3 or more cables each for multi phase power) would haveto be connected, one to the wiring terminals for each contactor. Theother end of those two cable sets then have to be paralleled. They couldbe paralleled by wiring the cable set from one contactor to the othercontactor, but then that contactor's terminals would have to be largeenough for the two cables. Alternatively, a junction box and splices orlug strips could be used. All of the cables have to be properlyprotected, most commonly in conduit. All of this leads to extra cost andtime for the installer. Using the internal buss bar greatly simplifiesthe cost and installation time, not to mention the additional savings ofputting the two contactors in the same enclosure, allowing one controlcircuit and set of actuators to be used for both.

Additionally, when the backup power source outputs much less power thanthe utility service provides (hence the need to protect againstoverloads), the portion of the contactor and buss bar used for thebackup power can be sized accordingly, thus giving additional savings.If the backup power input to the transfer switches are to be protectedby fuses or a breaker (not shown for 100 a) this can be easilyincorporated in the single enclosure whereas for two separate transferswitches the single backup power breaker complicates installation,requiring an additional enclosure for the breaker or wiring one transferswitch to the load side of the fuses or breaker located in the othertransfer switch.

Additionally, like the service entrance connections, the connectionsfrom the backup power source 97 usually must be protected by conduit,metal enclosures and the like which makes the single input to 100 a withinternal buss configuration easier and less expensive to install thanhaving to connect backup power via 105 to two separate transferswitches, each with its own enclosure. The backup power source 97outputs power via 105 which is coupled to the single backup power inputto 100 a. Power provided from the backup power source is monitored by 23e which communicates via 108 and the transfer switch 100 a is controlledvia communications link 110. 23 e may thus provide a measure of power(or current) being output by the backup power.

Returning now to FIG. 19, in some systems the rates for electricityprovided via both meters may change at different times and one or bothof the first and second meters may be utilized to interrupt power totheir respective loads, for example as controlled by the electricutility during heavy load conditions. The system of FIG. 19 (or FIG. 20or 21) will operate to provide either grid power or backup power to thevarious loads when one or both of the grid power sources fails. WhileFIG. 19 shows a center off position for the contactors 111 and 112 whichdisconnect power to all loads such as with a service disconnect andwhether or not incorporating all code requirements to be used as a trueservice disconnect it may be used and operate as described above. Forexample, in respect to 47 of FIG. 10, the center off position operatesin much the same manner as described above and will not be discussedextensively in the example below. If desired the center off position maybe eliminated from one or both contactors, as shown in FIG. 21. Forpurposes of the description of FIGS. 19 and 20 below it will be assumedthat both first meter 96 and second meter 98 receive power from the sameutility power grid, and the purpose of second meter 98 is to provide TOSmetered power to electric vehicle chargers, home battery backups (e.g.FIG. 12) and the like whereby the rate charged by the utility for thesupplied power is lower during the night and/or other low demand times.

The embodiment shown in FIG. 19 includes a normal billing power input104 from first meter 96 and a TOS power input 106 from second meter 98,and a backup power source input 105 from a backup power source 97.Transfer switch 100 has contactor 111 which operates to normally couplepower from 104 to 101 thereby providing power to normal billing rateloads. Transfer switch 100 also has contactor 112 which operates tonormally couple power from 106 to 102 thereby providing power to TOSbilling rate loads, in this example for one or more rapid (>20 A inputcurrent) chargers for electric vehicles, a home battery backup such asin FIG. 12 or the like. In this fashion the utility customer can electto charge such loads at night or other times when the rates are lower.

The charger(s) may operate with a simple 24 hour clock or a moreelaborate timer, and/or communications e.g. an internet connection, inorder to automatically charge the vehicle(s) during time periods whenlower cost power is available. As suggested above, (e.g. FIG. 12, 25 b,69, 70) the load control 25 or load control processor circuit 99 mayalso provide or assist with this functionality, allowing not only loadmanagement to minimize power consumption by devices, including powerstorage devices, from the grid during times when power costs are highbut to provide power to such devices when costs are low. Thefunctionality may also include capability to purchase and store powerfrom the grid in response to internet provided information when it ischeap or generate and store power when fuel is cheap, and use thatstored power when grid costs are high.

The load control processor (or chargers) may communicate with theutility or other sources to receive updated or real time rates and otherinformation such as high grid loading and brownout potential and adjustcharging in response thereto. With other utility arrangements theautomatic charging control may interact via one or more communicationslinks with power brokers who sell power to the customer, which power isthen delivered via the local utility's power distribution system to thecustomer. In this manner the customer may manually or automatically (viainternet connected computer) shop for the best power rates and timesboth from the local utility and from providers outside of the localutility. If the customer needs to have one or more vehicle chargedquickly the automatic charging may supersede or be given a higherpriority than other power uses. The use of an internet connection toobtain updated power rates vs. time will help to achieve low costcharging.

The transfer switch 100 couples the incoming power to the load controlprocessor circuit 99 via a connection 109. This may be done directly,for example connecting the supplied power on 104 (e.g. 240 volts singlephase, 60 Hz) to circuit 99, or by sensing and providing one or morepower parameter (e.g. ones of voltage, frequency and within a desiredtolerance) of the incoming power to circuit 99. Alternatively, thesupplied power on 106 or power parameters may be coupled via 125 tocircuit 99 instead of or with those from 104. The load control processorcircuit 99 is responsive to the input(s) to determine if the powerquality is acceptable and if not, it starts the backup power 97 viacommunications link 107 similar to 27 a and 27 c. When backup powersource 97 has come up to speed and is providing acceptable backup poweras load control processor circuit 99 determines via communications link107, the transfer switch contactors 111 and 112 are controlled via 110to switch from utility power to backup power. The control of 111 and 112may be together or separately as desired and if separately 111 and 112may be switched at different times. The load control processor circuit99 may receive and utilize parameters such as those described for 27 a,including one or more of peak voltage, RMS voltage, power (voltage orcurrent) frequency, power current and for rotating machinery powersources RPM in order to compute backup power readiness or other backuppower related information utilized by the processors 33 a&b, 37 orcircuit 99 instead of, in addition to or along with information fromload monitors and current sense circuits 23 a-i. The operation ofstarting the backup power and switching contactors 111 and 112, alongwith numerous alternative operations and variations in communications,components, combinations and connections, known to the person ofordinary skill in the art from the descriptions herein.

After the power loss and switching the contactors 111 and 112, the loadcontrol processor circuit 99 is preferred to operate to sense one ormore known parameter of the output power of the backup power source 97,to control one or more loads N. The N loads may be normal billing loadsand/or TOS billing loads, the control processor operating in order toprovide efficient operation while prevent overloading the backup power,and/or to remove an overload if one should occur, as described herein.When operating from grid power the load control processor circuit 99 ispreferred to prevent overloading of either or both the normal billingsupply and the TOS billing supply. When operating from backup power theload control processor circuit 99 is preferred to prevent overloading ofeither or both the normal billing supply output and the TOS billingsupply output of the transfer switch (assuming the backup power has thecapability of providing enough power to create such an overload) and toprevent overloading of the backup power source 97. Parameters of theoutput power include one or more of the instant and average: frequency,peak-peak and RMS current and peak-peak and RMS voltage of power beingoutput by one or more of the hot output connections, hot being the twocurrent outputs of a single phase system or the current phase outputs ofa multi phase system. The load control processor may also communicatewith environmental, user and miscellaneous devices 21 as describedabove.

As described herein, one or more instantaneous or non-instantaneousoutput parameter of the backup power (e.g. voltage, currents, VA, activepower, apparent power, power factor or watts) may be compared to themaximum and/or currently available output parameter(s) of the backuppower source to determine if a load can be connected without creating anoverload. Of course, some backup power source manufacturers do notprovide many parameter(s) so that must be taken into account. For somelower cost generators, only a steady state maximum parameter in watts oramps is provided, and then sometimes there is no identification ofdefinition of how or under what conditions it is determined. Forexample, the manufacturer may just say it is a 5000 watt peak, 3500 wattcontinuous output. There may be no explanation as to what peak orcontinuous mean. Thus, at times it is desirable for load controlprocessor 99 to further characterize the backup power source in itsactual installed operation by recording instances of overload for knownoutput loads.

The output of the backup power as determined in response to 23 e (orones of 23 e-i) may be compared to a manufacturer's specified maximumavailable output, as derated (if used), for various environmentalfactors, to determine if the backup power is already overloaded and ifso may also determine how much, by a numeric value, over a threshold,over an amount of time or another amount. When rotating machinery typebackup power source is used, the frequency of the backup power can besensed and used to determine overloads and if so may also determine byone or more of how much by a numeric amount, over a threshold, for anamount of time, or another amount. One or more of these determinationsmay then be recorded, stored or otherwise taken into account in ordermore accurately characterize the capabilities, and in particular themaximum output capabilities of the backup power source. An intentionaltesting routine may also be utilized, either manually initiated by anoperator or automatically upon the occurrence of one or more particularevent e.g. at the start of a power outage, to perform characterization.The testing routine may intentionally increase loading of the powersource to near or over its rated or previously determined maximumcapability parameter with that parameter then being updated or moreaccurately detailed to reflect the backup power source response to thetesting, thereby producing one or more improved backup parameter(s).This improved parameter may be utilized to control backup powerconnected loads.

FIG. 19 also shows alternate and optional additional load monitorlocations 23 f-i in the transfer switch 100. In particular, 23 h and 23i are preferred to be utilized in place of 23 e in order that currentchanges can be measured when powered from the grid or backup power via101 or 102. When a given load is turned on and off whether powered bythe grid or the backup power, that load may be characterized.Additionally, the characterization will be less susceptible tointerference from load changes on the other output. That is, whenmeasuring a load connected via 101, loads connected via 102 will nottend to interfere to a significant amount, if at all, with thecharacterization. Further, as taught above with respect to 23 a, 23 band 23 d, by having the ability to measure and characterize loads whilebeing powered from grid 96 via 23 h and 98 via 23 i, the load may becharacterized at any time. For example, characterization may beperformed one time when powered from the stable power grid (e.g. atinstallation), or characterized repeatedly during normal use whilepowered by the grid.

The repeated characterization, as well as use of a testing routine, areparticularly useful for loads which change due to environmental factorsas described above e.g. an air conditioner may be characterized andrecorded, stored or otherwise utilized during a hot summer afternoon andthus if grid power fails the load parameters will be up to date for thatparticular set of environmental parameters. Alternatively, 23 e, 23 hand 23 i may be located outside of the transfer switch. And as desiredto practice the invention in a particular embodiment to achieve aparticular set of capabilities the load control processor circuit 99 mayreceive input from and provide optional output to: Environmental User &Misc. Devices 21 via 28 c, Backup Power 97 via 107, load monitor 23 e(and/or ones of 23 f-i), input 109 from 96 via 104, providing output 110to the contactors 111 and 112 and voltage and other backup powerparameters via 125. In some backup power devices, the output currentand/or other load related parameters are available directly to circuit99 via communications link 107 thus eliminating the need for some ofthese devices and connections. The load control processor circuit 99also has N output(s) 103 to N controlled normal and/or TOS loads. Whileit is preferred that both normal and TOS loads be controlled, the loadcontrol processor 99 may control one or the other.

In addition to the advantages above the preferred embodiment of FIG. 19has novel, and believed commercially valuable features. The use of twomechanically linked electromechanical contactors 111 and 112 controlledby load control processor 99 give the ability to simultaneously switchboth the normal and TOS billing loads from their metered power inputs tobackup power. This mechanical linking may be provided by utilizing acommon linkage or shaft which is actuated by two solenoids, one solenoidfor normal operation and the other for backup power operation, willprovide a quick and efficient latching operation which eliminates manyproblems arising by using two separate transfer switches, each with itsown controller having operating parameters which must be set by theinstaller or operator, one or more contactors and associated actuator.

In some systems it will be desirable to switch one of contactors 111 and112 a delay time after the other or to a different position as theother. This for example will reduce the loading on the power sourcebeing switched to, in order to reduce the instant loading thereon. Inanother example it will keep one switched load on one power source (e.g.such as the generator) while the other is switched to the other powersource (e.g. such as the grid). This delay will be particularly usefulto reduce the surge loading of the power sources when switching and ifone of the loads being currently powered will be impacted by a switchingtransient, and the switching of the corresponding contactor 111 or 112may be delayed until a more suitable time. If such delayed operation isdesired the common mechanical linkage is preferred to be replaced withseparate switching mechanisms, each operated independently of the otherby a single or separate controllers.

The operating parameters in two prior art controllers may interact witheach other thereby causing problems. For example, many prior arttransfer switch controllers are designed to send a start signal to abackup genset, wait to see if it starts and if it does start and itsoutput within desired parameters the controller switches the contactor.If the genset does not start or provide a proper output it is turned offand the controller waits for a known time, e.g. two minutes, beforeattempting a restart. If only one of a plurality of prior artcontrollers is allowed to start and stop the genset, the other may notsee power when it thinks it should and flag a failure. If bothcontrollers are allowed to start the genset either controller may flag afailure because the other started or stopped the genset. Load controlprocessor 99 may provide backup power source start and a plurality ofindependent contactor control capability which overcomes these prior artcontroller problems if desired.

The FIG. 20 one line drawing of the transfer switch 100 as described inrespect to FIG. 19, and further includes a dual watthour meter 113including watthour meters circuits 96 a and 98 a the inputs of which areinternally bussed in 113 to receive grid power from 12 via a single setof connections (e.g. lugs). Each meter 96 a and 98 a has an output 104and 106 respectively to a service connect device 123 having individualdisconnects 123 a and 123 b. In this manner both service entrances fromtheir respective meters may be simultaneously disconnected andreconnected via control 123 c. If desired, individual disconnects may beutilized. This will be particularly useful if one or more critical loadis fed by one of the services entrances, for example a fire pump whereinthe disconnect should be locked (e.g. via a padlock) in the connectedcondition.

FIG. 22 shows an example embodiment of the dual watthour meter 113including the front or face (left), right side (middle) and back side orbase (right) views, including its case, as configured for use withsingle phase 240 volt power. Other voltages and/or power phases may beaccommodated as desired. The meter consists of a case comprising a metercover 127 and baseplate 128 as well as a mounting ring 128 a from whichconducting (e.g. metal) blades 104 a, 106 a and 129 a extend. Ratherthan adopting a currently standardized meter blade pattern for a singlecircuit revenue meter, the blades are preferred to be arranged in novelpatterns, for example as shown in FIG. 22, which patterns are believedto be unique as compared to standard revenue patterns, thus preventing asingle circuit meter and the instant dual meter from being interchangedin each other's sockets and thereby creating a potentially hazardoussituation. The baseplate is preferred to be of insulating material e.g.a plastic such as Bakelite. FIG. 22 includes the base view (right) of113 showing baseplate 128 and mounting ring 128 a with blade arrangement129 a via which power is input to both meters 96 a and 98 a, as well asAlternate 113 with blade arrangement 129 b and 129 c for power inputs toNormal meter 96 a and TOS meter 98 a respectively. The normal outputblades 104 a and TOS output blades 106 a are also shown, as well as thecommon blade 130.

The meter sockets for 113 and for Alternate 113 are not shown but willhave an arrangement of conducting meter jaws, which the blades of 113plug into, which arrangement resembles the mirror image of thearrangement of blades of 113 (or Alternate 113 if used) as will be knownin the art from the teachings herein. It is preferred that the overallsize, dimensions and construction of 113 are similar to single smartrevenue meters which are commonly finding use in U.S. electric utilitysystems, but with the novel inclusion of a plurality of revenue metersas will be known to the person of ordinary skill in the art from theteachings herein. It will be understood that the particular details ofdimensions, construction and design may be resorted to for use by aparticular power utility as desired without departing from the inventiveconcepts herein.

The dual meter 113 has readouts 96 b and 98 b corresponding to anddisplaying measurements made by the two watthour meters 96 a and 98 arespectively. The readouts may be of mechanical types, for example suchas analog vertical (like a Hobbs meter) or round dials or variousdigital types, but are preferred to be LED or backlit LCD digital(including color and/or graphic) types. The watthour meter readouts arepreferred to be configured and labeled to facilitate reading by utilityemployees, for example by physical appearance e.g. arrangement,surrounding color and color display. If desired, the displays 96 b and98 b may be combined into one display device showing a plurality of setsof numbers, or may utilize a single display which is cycled to displaythe readings of the plurality of watthour meters one or a few at a time.The dual meter 113 may share with, include, perform, control and displayother functions as desired, and in particular smart meter capabilitiesas will be known to one of ordinary skill in the art from the teachingsherein. User interface controls may be achieved with devices included in113 e.g. such as touch pads, switches, shaft encoders and the like orwirelessly. For example, wireless communications enabling meter readingand operating with various internal meter functions, e.g. load shedding,may be incorporated.

The middle view of FIG. 22 shows the dual meter case including a metercover 127 which is preferred to comprise a transparent and weather proofmaterial e.g. glass, polycarbonate plastic or the like for at least aportion of the face to facilitate viewing the readouts 96 b and 98 bwith the entirety of the case being weatherproof. The middle view alsoshows a meter baseplate 128 (not to be confused with a meter base orsocket) to which the meter cover is affixed and from which the meterblades protrude in order to facilitate mating with the jaws of the metersocket (113 a of FIG. 20) as meter and socket mating is known in theart. The mounting ring 128 a may be a part of the baseplate 128, or partof the meter cover 127 or a separate component as desired. The (upper)right view shows the meter blades 129 a for receiving input power, andproviding normal billing output via blades 104 a, TOS billing output viablades 106 a and common connection 130, e.g. the neutral in a 240 voltsystem. The meter enclosure (not to be confused with the meter case) isnot shown but is preferred to be of metal construction meeting one ofthe various NEMA standards (e.g. 3R indoor & outdoor use) with the metersocket being suitably affixed in a position allowing the meter to beplugged into the jaws of the meter socket, the resulting position of themeter facilitating reading by the customer or utility.

The novelty and advantages of the dual meter 113 is further understoodby comparison to physically and electrically separate revenue meters ascommonly used in stacks and rows for apartment buildings, one for eachcustomer. In 113 the separate metering capability is preferred to becombined into one physical device containing 96 a & b and 98 a & b whichdevice mates with a single dual meter socket 113 a, preferred to have asingle grid input. The inputs of meters 96 a and 98 a are connected tometer blades 129 a in the meter base and/or cover. The meter 113 ispreferred to have two or more separately metered output blade sets, suchas 104 a and 106 a, that is, it is preferred to have one set for eachmeter. This novel configuration is cost effective in that the internalbuss or other connection (inside the meter case and/or baseplate) fromthe single grid input via 129 a to the inputs of the meters (e.g. 96 aand 96 b) eliminates need for one or more a separate junction boxes tomake connections from the grid service to the inputs of separatelycased, socketed and enclosed meters, all of which are to be enclosed andwired according to code plus the attendant installation costs, as wellas requiring sealing by the utility.

Alternatively, the dual meter may be one physical device having a singlecase including a cover and a baseplate with the baseplate and metersocket having an individual grid input and a corresponding output foreach meter. This is shown in Alternate 113 where there are two inputsvia blades 129 b for normal meter 96 and 129 c for TOS meter 98. It willbe useful to buss or otherwise connect the plurality of grid inputs inthe corresponding meter socket thus simplifying installation andreducing costs. For example, a single high current (e.g. 520A continuous600 A intermittent) grid feed can connect to high current lugs on themeter socket which busses that feed to a 320/400 A meter input and a 200A meter input, with each meter having a corresponding output. The320/400 A output may for example be connected to one or more vehiclechargers and the 200 A output connected to the normal loads. The loadcontrol processor 99 will control the loading to ensure that neithermeter rating is exceeded and also that the total service rating (520 Acontinuous 600 A intermittent) is not exceeded. While these numbers mayseem excessive for a home, it is envisioned that as battery chargingcapability for electric vehicles improve over the next several years, itwill not be unusual to see the need for 240 volt single phase 320/400 Aservice for a plurality of, or even single vehicle, charging stations.While higher voltage three phase would be a much preferable serviceconnection, three phase is not common for residential neighborhoods andswitching entire neighborhoods, or even one house in a neighborhood, tothree phase is very expensive. Nevertheless, it will be understood thatthe instant invention may be utilized with multi-phase power ifavailable.

It will be understood that when currents reach continuous 400 amps andabove, it is difficult to construct a reasonable size set of blades andjaws to handle that amount of current. Along with the large size, thenecessary clamping pressure on the blades required to be provided by thejaws becomes difficult to deal with in terms of inserting and removingthe meter. Larger blades, jaws and meter sizes as well as complexmechanical designs to deal with the pressures could be resorted to,however it will be understood that a more reasonable approach in termsof cost and efficiency is to use current sensing devices (e.g. currenttransformers) and voltage contacts in the meter socket for high currentconductors with one set of input blades connecting only to the currentsensing devices and voltage contacts for each high current circuit willbe particularly useful. In this manner the high current conductors maysimply pass through the meter enclosure without having to be routedthrough the meter itself. The corresponding watthour meter may thendetermine the power used in response to the current sensing devices andvoltage contacts. High current Is defined in this respect as systemsrated at continuous 400 amps and above for at least one meter. Anotheralternative consists of a set of input blades for each high current(≥400 A continuous) meter (responding to the current and voltagecontacts for that circuit) and another set of blades for one or morelower current (<400 A continuous total) meters. Of course, If desiredcurrent sensing devices and voltage contacts may be located in the meterenclosure for all of the separately metered power feeds.

FIGS. 23A-E show an exemplary power switching device may be desirable tobe utilized to practice various embodiments of the invention to achievea particular set of functionality and cost. While various forms of powerswitching will be known to the person of ordinary skill in the art fromthe teachings herein which may be utilized e.g. with the transferswitches 15, 47, 100 and 100 a, to practice the invention with a desireddegree of performance, reliability and cost, the power switchingembodiments described herein with respect to FIGS. 23A-E will bedesirable to be utilized to practice various embodiments of theinvention, and in particular those utilizing a center off capability.FIGS. 23A-D show a simplified side view mechanical drawing demonstratingthree states of a double throw with center off contactor 114 which alongwith FIG. 21E will aid in the understanding of novel features of thetransfer switch 100. In FIG. 21A, the swinger portion of the contactoris shown in the center off position (stationary contacts A and B are notshown).

The contactor 114 includes a swinger 115 which pivots up and down aboutan insulated pivot point. The swinger serves as and has affixed to theright end the C contacts and is electrically conductive with a flexiblecable attachment from below the pivot point to terminal C (not shown in23A). As used herein in respect to transfer switch power circuits,contacts are the mechanical or solid state parts of the contactor whichelectrically switched to open and close high current power circuits.Power terminals are utilized for connecting a set of power carryingwires (or cables) and include screws, bolts or other fastening devicesto allow an installer to make the wire connections. This is as comparedto a manufactured connection such as a buss bar which is intendedalready be connected by the manufacturer before installation in thefield. The conductivity thus extends from the terminal C via theflexible cable and continuing through and on to the right to the two Ccontacts at the right end of 115. As seen in FIG. 23B for the center offposition the C contacts are mechanically positioned between the upper A1contact and the lower B1 contact. These contacts are preferred to bemade of silver layered on or plated on brass or other highly conductivemetal construction which is resistant to pitting, corrosion and arcingas is well known in the art. In the particular embodiment shown, theswinger includes upper and lower arms between the pivot point and thecontact, the arms passing respectively above and below an insulated cam116 which is affixed to a shaft 117. The arms are preferred to bespringy and somewhat flexible in order that when the cam holds theswinger contact against the A or B contact, the spring tension holds thecontacts firmly together. The shaft rotates a short distance clockwiseor counter clockwise to cause the small end of the cam to rotate upwardand downward and thereby push against the upper or lower arm thus movingthe swinger up or down as shown in FIGS. 21C and D respectively. Otherarrangements of insulated and conductive portions and number of contactsof the swinger and contact(s) C may be resorted to as desired to achieveparticular levels of performance, reliability and cost.

The swinger 115 further includes a telescoping, spring loaded ormagnetically biased shaft 118 on the left end, the end of the shaftpressing against an insulated detent plate 119 to maintain the positionof the swinger once it has been moved into position by the cam 116.While a spring is shown inside the telescoping shaft, it may be externalto the shaft or replaced by opposing internal or external strong (e.g.Neodymium) magnets disposed at or near both ends of the telescopingshaft. The detent plate has three detents corresponding to the threeON-OFF-ON switch positions. If desired, the center off detent of 119 maybe eliminated. Shaft 118 is preferred to cause swinger 115 remain in thecurrent position without cam pressure until it is caused to change toanother position. Alternatively, 118 may be spring or magneticallybiased to return to the desired one of the three positions in theabsence of being forced by the cam to a particular position by changingthe design of the detent plate 119 such that without cam pressure thetelescoping shaft 118 will force the swinger to the desired position.That change may require continuous cam pressure to hold the swinger inthe other positions. If continuous cam pressure is undesirable, then oneor more electromagnets may be disposed behind (on the left side of) thedetent plate 119 to hold the swinger in position by attracting themagnet located at or near the left end of shaft 118. When power failsthe electromagnet will no longer hold the swinger in that position andthe telescoping shaft will return it to the desired (e.g. center off orgrid) position.

It is preferred that the spring or magnetic force as well as the shapeof the detent cooperate in order to flex the swinger's springy arms inorder to hold the contacts firmly together with pressure when in the Aand B contact positions, even if the power is removed from the solenoidaccordingly conserving power and allowing it to return to an unpoweredposition. Other manners of holding pressure on the contacts when in theA and B contact positions may be utilized as desired to achieve aparticular level of performance at a particular cost. The swinger, beingelectrically connected to a common contact C via a flexible cable, thusenables contactor 114 to connect terminal C to either the contact A orthe contact B or neither depending on the position of the cam 116. FIG.23C shows the contactor 114 swinger locked in the A contact position and23D shows contactor 114 swinger locked in the B contact position.

FIG. 23E shows a simplified mechanical drawing of a view of thecontactors and busses represented in the schematic diagram of thetransfer switch 100 a (which does not show a center off position), asviewed from the contact side. The individual single pole contactor 114of 23A-D is similar to each contactor set (1-4) of 21E. That is, 23Eshows two double pole, double throw contactors suitable for use with asingle phase 240 volt transfer switch. The first two pole contactorcomprises terminals A1, A2, B1, B2, C1 and C2 and the second comprisesterminals B3, B4, C3 and C4. FIG. 21E buss bars 124 and 126 eliminatethe second contactor need for terminals (A3 and A4) with a manufacturedconnection to the A contacts to reduce cost and installation time asdiscussed above. Alternatively busses 124 and 126 may be replaced withcables or other connections which are affixed in a low cost manner e.g.soldering, brazing or welding. Solenoids A 120 and B 121 are connectedvia one or more lever to the shaft 117 in order to rotate it to the Aand B contact positions respectively. Although the contactors oftransfer switch 100 a are shown without a center off position, thecontactor of FIG. 23E can be converted to include a center off positionby using a plate 119 (not shown in 23E) with three detents and a centeroff solenoid 122, also connected to shaft 117 by a lever. Solenoids120-122 may be replaced by a stepper motor if desired however it shouldbe kept in mind that opening and closing contacts should be performedquickly and forcefully in order to minimize arcing.

The several exemplary simplifications and operational related drawingsand written descriptions of exemplary embodiments of the invention usedherein are not to be considered limiting of the invention as will beknown to the person of ordinary skill in the art. The principles andinventive concepts of the present disclosure may be implemented usingany number of techniques, whether currently known or which may laterbecome known.

Although this invention has been described in its preferred embodimentwith a certain degree of particularity, with specific advantages andvarious embodiments it is understood that the invention is not solimited and the present disclosure of the preferred embodiment with itsvarious benefits, features and capabilities has been made by way ofexample and other technical advantages will become apparent to one ofordinary skill in the art after review of the Figures and description.

Numerous changes in the details of construction and the combination andarrangement of parts including some or all of the enumerated advantagesmay be resorted to and components arranged separately or integratedtogether as well as performing steps in any suitable sequence in orderto meet a particular level of performance, reliability and cost withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

To aid the Patent Office and readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicant wishesto note that he does not intend any of the appended claims or claimelements to invoke 35 U.S.C. 112(f) unless the words “means for” or“step for” are explicitly used in the particular claim.

The invention claimed is:
 1. A dual transfer switch for use in a home orbusiness which receives single or multiple phase A.C. electric powerfrom at least a first power source, the A.C. electric power having astandard frequency and voltage and powering a group of loads via a firstrevenue meter and a second group of loads via a second revenue meter,the dual transfer switch comprising: a) a plurality of contactors, eachcomprising at least two poles and break before make double throwoperation, a first contactor of the plurality of contactors having a setof grid connection power terminals receiving hot wires of electric powerfrom the first power source via a normal billing revenue meter and asecond contactor of the plurality of contactors having a set of gridconnection power terminals receiving hot wires of electric power fromthe first power source via a time of service revenue meter, b) the firstand second contactors each having backup power contacts which aremanufactured with an electrically paralleled configuration and only oneshared set of backup power terminals receiving hot leads of A.C.electric power from a backup power source, c) the first contactor havinga set of normal output power terminals via which normal loads arepowered, the second contactor having a set of time of service outputpower terminals via which time of service loads are powered, d) aprocessor circuit having stored parameters, executing a program andoperating to determine when grid power supplied via one or both of thenormal billing revenue meter and the time of service revenue meter doesnot meet acceptable parameters and in response controlling the first andsecond contactors to connect to the backup power contacts to supply theA.C. electric power from the backup power source via the normal outputpower terminals and the time of service power terminals, e) an interfacecircuit whereby an installer inputs a maximum power output parameter forthe backup power source, f) the processor circuit responsive to themaximum power output parameter and an amount of power being supplied bythe backup power source to determine an amount of remaining power thebackup power source can supply without an overload, with the processorcircuit further connecting and disconnecting the normal loads and/or thetime of service loads in order to prevent overload of the backup powersource.
 2. The dual transfer switch of claim 1 wherein both normal loadsand time of service loads are connected and disconnected by theprocessor circuit.
 3. The dual transfer switch of claim 1 wherein onlynormal loads or only time of service loads are connected anddisconnected by the processor circuit.
 4. The dual transfer switch ofclaim 1 wherein the processor circuit is responsive to a current sensorcircuit configured to respond to current flowing at the set of backuppower terminals in order to determine the amount of power being suppliedby the backup power source.
 5. The dual transfer switch of claim 1wherein the processor circuit is responsive to a first current sensorcircuit physically located at the set of normal output power terminalsand responsive to the current flowing from the set of normal outputpower terminals, and the processor circuit further responsive to asecond current sensor circuit physically located at the set of time ofservice output power terminals and responsive to current flowing throughthe set of time of service output power terminals in order to determinethe amount of power being supplied by the backup power source.
 6. Thedual transfer switch of claim 1 wherein the processor circuit isresponsive to the frequency of the A.C. electric power from the backuppower source in order to determine the overload and in response theretodisconnect one or more of the normal loads and/or time of service loads.7. The dual transfer switch of claim 1 wherein the processor circuit isresponsive to a first current sensor circuit physically located at theset of normal output power terminals and responsive to current flowingthrough the set of normal output power terminals, the processor circuitfurther responsive to a second current sensor circuit physically locatedat the set of time of service output power terminals and responsive tocurrent flowing through the set of time of service output powerterminals.
 8. The dual transfer switch of claim 1 wherein the first andsecond contactors have different maximum current ratings.
 9. The dualtransfer switch of claim 1 wherein the first and second contactors aresimultaneously actuated by a common shaft or mechanical linkage.
 10. Adual transfer switch for use in a home or business which receives singleor multiple phase A.C. electric power from at least a first powersource, the A.C. electric power having a standard frequency and voltageand powering a group of loads via a first revenue meter and a secondgroup of loads via a second revenue meter, the dual transfer switchcomprising: a) a plurality of contactors, each comprising at least twopoles and break before make double throw operation, a first contactor ofthe plurality of contactors having a set of grid connection powerterminals receiving hot wires of A.C. electric power from the firstpower source via a normal billing revenue meter and a second contactorof the plurality of contactors having a set of grid connection powerterminals receiving hot wires of A.C. electric power from the firstpower source via a time of service revenue meter, the first and secondcontactors having different power ratings, b) the first and secondcontactors sharing a single set of backup power terminals receiving hotleads of A.C. electric power from a backup power source, c) the firstcontactor having a set of normal output power terminals via which normalloads are powered, the second contactor having a set of time of serviceoutput power terminals via which time of service loads are powered, d) aprocessor circuit having stored parameters and executing a program andoperating to determine when grid power supplied via one or both of thenormal billing revenue meter and the time of service revenue meter doesnot meet acceptable parameters and in response controlling thecontactors to connect to the backup power terminals to supply the A.Celectric power from the backup power source via the normal output powerterminals and the time of service power terminals, e) an interfacecircuit whereby an installer inputs a maximum power output parameter forthe backup power source, f) the processor circuit responsive to themaximum power output parameter, a first current sensing circuit sensingcurrent output from the normal output power terminals, and a secondcurrent sensing circuit sensing current output from the time of serviceoutput power terminals, the processor circuit operating to connect anddisconnect the normal loads and the time of service loads withoutcreating an overload of the backup power source.
 11. The dual transferswitch of claim 10 wherein the processor circuit is responsive to thefrequency of the A.C. electric power from the backup power source inorder to determine the overload and in response thereto disconnect oneor more of the normal loads and the time of service loads.
 12. The dualtransfer switch of claim 10 wherein the processor circuit monitorscurrent change sensed by the first current sensing circuit as theprocessor circuit turns a known load on and off in order to characterizethe current drawn by the known load.
 13. The dual transfer switch ofclaim 10 wherein when the first contactor selects power provided via thenormal billing revenue meter the processor circuit monitors currentchange sensed by the first current sensing circuit as the processorcircuit turns a known load on and off in order to characterize thecurrent drawn by the known load.
 14. The dual transfer switch of claim10 wherein when the first contactor selects power provided via thebackup power source the processor circuit monitors frequency change ofthe A.C. electric power from the backup power source as the processorcircuit turns a known load on and off in order to characterize themaximum current output of the backup power source.
 15. The dual transferswitch of claim 10 wherein when the first contactor selects powerprovided via the backup power source the processor circuit monitorsenvironmental parameters as well as frequency change of the A.C.electric power from the backup power source as the processor circuitturns a known load on and off in order to characterize the maximumcurrent output of the backup power source for those environmentalparameters.
 16. The dual transfer switch of claim 10 wherein for each ofthe first and second contactors the set of backup power terminals areconnected to respective backup power contacts having a different powerrating than respective normal grid power contacts connected to thenormal billing revenue meter and also different than respective time ofservice grid power contacts connected to the time of service revenuemeter.
 17. The dual transfer switch of claim 10 wherein the first andsecond contactors are simultaneously actuated by a common shaft ormechanical linkage.
 18. A dual transfer switch for use in a home orbusiness which receives single or multiple phase A.C. electric powerfrom at least a first power source, the A.C. electric power having astandard frequency and voltage and powering a group of loads via a firstrevenue meter and a second group of loads via a second revenue meter,the dual transfer switch comprising: a) a plurality of ON-OFF-ONcontactors, each comprising at least two poles, a first contactor of theplurality of contactors having a set of grid connection power terminalsreceiving hot wires of A.C. electric power from the first power sourcevia a normal billing revenue meter and a second contactor of theplurality of contactors having a set of grid connection power terminalsreceiving hot wires of A.C. electric power from the first power sourcevia a time of service revenue meter, b) the first and second contactorseach having backup power terminals receiving hot leads of A.C. electricpower from a backup power source, c) the first contactor having a set ofnormal output power terminals via which normal loads are powered, thesecond contactor having a set of time of service output power terminalsvia which time of service loads are powered, d) a processor circuithaving stored parameters and executing a program and operating todetermine when grid power supplied via one or both of the normal billingrevenue meter and the time of service revenue meter meets acceptableparameters and in response controlling the first and second contactorsto select grid power by connecting to respective grid connection powerterminal to supply the A.C. electric power from the first power sourcevia the normal output power terminals and the time of service powerterminals, e) the processor circuit operating to determine when gridpower supplied via one or both of the normal billing revenue meter andthe time of service revenue meter does not meet the acceptableparameters and in response controlling the first and second contactorsto select backup power by connecting to the backup power terminals tosupply the A.C. electric power from the backup power source via thenormal output power terminals and the time of service power terminals.19. The dual transfer switch of claim 18 wherein the processor circuitoperates to determine when grid power supplied via one or both of thenormal billing revenue meter and the time of service revenue meter doesnot meet acceptable parameters and to further determine when backuppower from the backup power source does not meet acceptable parametersand in response control the first and second contactors to selectrespective off positions with the processor continuing to monitor gridpower and backup power and when one of the grid power and backup powermeets acceptable parameters the processor controls the contactors toselect the corresponding one of the grid power and backup power meetingacceptable parameters to be supplied via the normal output powerterminals and the time of service power terminals.
 20. The dual transferswitch of claim 18 wherein the processor operates to control the firstand second contactors to select respective off positions while adifferent power source supplies power to at least one of the normalpower loads and the time of service loads.